for the beads question, since blue is not changed in both scenarios, look at them as units + ? red, blue = 2u, red = 3u + 56 yellow, blue = 2u, red and yellow = 7u which means 7u - 3u = 4u 4u = 56 (yellow added) 1u = 56 ÷ 4 = 14 3u = 3 x 14 = 42 (total red after adding) 42 - 9 = 33 (take away original red) 33 red beads added
pretty neat. I guess unit method is what they teach in Singapore math. I, for example, didn't learn unit method for this type of questions. We learned to use variables, then expressing one variable in terms of others, eventually solving the equation. But after seeing unit method, I feel like this is much better way to teach this type of questions as it is less abstract and it instil intuition as opposed to solving for a variable. Good stuff!
Start with 9 beads, add 33 red beads, new total is 42. If 2/5 of total beads then is equal to blue beads, which is 16.8? How does the beads have fractional number? Then take 42 and add 56 yellows, new total is 98. 2/9 is blue, so blue beads are 21.778? Wrong answer again?
Great explanation. What I did was I let y be the red beads added, and x be the number of blue beads. So when 56 yellow beads were added, I got two equations: x/(x+56+9) = 2/9 and x/(9+y+x) = 2/5. I tried solving for x but got 7x=130 which does not give a full number. Not sure if algebra can work for this
11:36 After seeing the bar graph method I remember why I prefer using it so much since it uses only 2 simple graphs and 3 lines of simple calculations. Even after skipping some lines, I used 16 lines to get the answer when using algebra. But maybe it’s possible that I could’ve shorten it somehow
I was expecting something like this 2021 question :p Helen and Ivan had the same number of coins. Helen had a number of 50-cent coins, and 64 20-cent coins. These coins had a mass of 1.134kg. Ivan had a number of 50-cent coins and 104 20-cent coins. (a) Who has more money in coins and by how much? (2) (b) given that each 50-cent coin is 2.7g more heavier than a 20-cent coin, what is the mass of Ivan's coins in kilograms? (2)
question on arranging the fractions should not be 3/4 difficulty level.. it is about learning the right approach to solve the math questions.. 9/8 = 1 1/8 5/4 = 1 1/4 1 1/9 after converting them to mixed numbers, all you have to do is compare the fractional part (1/8, 1/4 and 1/9) 1/4 is largest, 1/8 is next, 1/9 is smallest.. therefore, 5/4, 9/8, 1 1/9
Solution for the question on beads: Quantity Unchanged Concept with Equal Fraction Concept: We compare the number of beads right after some RB were added and after 56 YB were added When 56 YB were added, No BB was added Hence, The number of BB is an unchanged quantity From the 2nd sentence, The numerator of 2/5 represents the number of BB after some RB was added From the 3rd sentence, The numerator of 2/9 represents the number of BB after 56 YB were added Hence, equalise the numerators However, the numerators are already the same Hence, 2/5 of total (after RB added) = 2/9 of total in the end BB = 2u Total (after RB added) = 5u Total in the end = 9u In this comparison, The diff in the total number of beads is due to the addition of 56 YB Hence, 9u - 5u = 56 4u = 56 1u = 56 ÷ 4 = 14 Since there were only RB and BB before adding 56 YB, RB (after RB added) = Total (after RB added) - BB = 5u - 2u = 3u = 3 x 14 = 42 From the 1st sentence, There were 9 RB at first Hence, RB added = RB (after RB added) - RB at first = 42 - 9 = 33 (Ans)
Start with 9 beads, add 33 red beads, new total is 42. If 2/5 of total beads are blue beads, which is 16.8? How does the beads have fractional number? Then take 42 and add 56 yellows, new total is 98. 2/9 is blue, so blue beads are 21.778? Wrong answer again? The amount of blue beads don't match?
I tot it's worth highlighting.. while it may seem like the current employment situation favor skills/experience over educational qualification, plus thrs underemployment issues as well (at least frm my own personal employment experience), clearly those aren't the valid reasons for people to discount the efforts of learning and the importance of the subject.. if all employers and employees think this way, the society is set to fail.. Such dangerous mentality shld be discouraged at all costs.
The answer to the Red and Blue beads question: 61 Red beads were added, but the question is WRONG. Start off with 9 beads (Red & Blue) Add 61 Red beads, total is now 70 beads, 2/5 are Blue beads (28 Blue beads) Add 56 Yellow beads to the 70 beads, total is now 126 beads, 2/9 are Blue beads (also 28 Blue Beads) The method to find the unknown of Red beads added: Where x is the number of Red beads added, we also know that Blue beads remain constant, Blue beads is 2/5 * (9+x) Blue beads is also 2/9 * (9+56+x) 2/5 * (9+x) = 2/9 * (65+x) Solving x: 8x=488 x=61 (Red beads added) 61 Red beads were added. But we started with 9 beads only, how did we have 28 Blue beads?
salute the guy with smart mental cal, cn try compete with ms munchie.. as for the guy majoring in econs who dk math modeling and basic math, hmm maybe he is either jus too stressed in front of camera or doing it on purpose for entertainment.. if not, rlly doesn't do any justice to the rest of us who scored A too
That abacus guy who could do sums in his head is so attractive (people who can do math is attractive fr) if I was Brenda I’d be fangirling
Wow. The guy who could the sums in his head so quickly? 😮😮😮😮 my mind cannot comprehend.
Wait till u see the human calculator 😂
i can see the abacus in my head, i was like nani
I finally found a guy who can match my math ability to do mental calculations with just the mind
@@nigelmorais7722 amazing. Your talent should be recognized.
Help its abacus fr. I also do it. But there's no link between IQ and that
for the beads question, since blue is not changed in both scenarios, look at them as units
+ ? red, blue = 2u, red = 3u
+ 56 yellow, blue = 2u, red and yellow = 7u
which means 7u - 3u = 4u
4u = 56 (yellow added)
1u = 56 ÷ 4 = 14
3u = 3 x 14 = 42 (total red after adding)
42 - 9 = 33 (take away original red)
33 red beads added
pretty neat. I guess unit method is what they teach in Singapore math. I, for example, didn't learn unit method for this type of questions. We learned to use variables, then expressing one variable in terms of others, eventually solving the equation. But after seeing unit method, I feel like this is much better way to teach this type of questions as it is less abstract and it instil intuition as opposed to solving for a variable. Good stuff!
Start with 9 beads, add 33 red beads, new total is 42. If 2/5 of total beads then is equal to blue beads, which is 16.8? How does the beads have fractional number?
Then take 42 and add 56 yellows, new total is 98. 2/9 is blue, so blue beads are 21.778? Wrong answer again?
@@CW91 42/3=14 lah, bro fail primary 2 math is it
@@hongtaozhong1172 ?
Great explanation. What I did was I let y be the red beads added, and x be the number of blue beads. So when 56 yellow beads were added, I got two equations: x/(x+56+9) = 2/9 and x/(9+y+x) = 2/5. I tried solving for x but got 7x=130 which does not give a full number. Not sure if algebra can work for this
11:36 After seeing the bar graph method I remember why I prefer using it so much since it uses only 2 simple graphs and 3 lines of simple calculations.
Even after skipping some lines, I used 16 lines to get the answer when using algebra. But maybe it’s possible that I could’ve shorten it somehow
The guy who can mentally do all the easy questions... Why didn't you test him using the most difficult question? We will like to see how he solved it
Damn....I took design and have not touched maths in a million years. So miss being able to do these kinds of questions
Could you solve these too?
the arrange the largest to smallest one and just convert all to mixed fraction, thn compare 1/4 ,1/8,1/9
don't even need to convert haha. Just -1 from all the numbers and compare.
Lol Brenda as a tutor
I was expecting something like this 2021 question :p
Helen and Ivan had the same number of coins. Helen had a number of 50-cent coins, and 64 20-cent coins. These coins had a mass of 1.134kg. Ivan had a number of 50-cent coins and 104 20-cent coins.
(a) Who has more money in coins and by how much? (2)
(b) given that each 50-cent coin is 2.7g more heavier than a 20-cent coin, what is the mass of Ivan's coins in kilograms? (2)
@@Poochadragon123b is wrong ☠️☠️☠️
As someone who took the 2021 math paper, i can def say that this was one of the eaisest questions on the paper 😢
@@Poochadragon123 lmao you edited your answer from 1.242kg to 1.026kg, which is the right answer. How shameful
question on arranging the fractions should not be 3/4 difficulty level.. it is about learning the right approach to solve the math questions..
9/8 = 1 1/8 5/4 = 1 1/4 1 1/9
after converting them to mixed numbers, all you have to do is compare the fractional part (1/8, 1/4 and 1/9)
1/4 is largest, 1/8 is next, 1/9 is smallest..
therefore, 5/4, 9/8, 1 1/9
Solution for the question on beads:
Quantity Unchanged Concept with Equal Fraction Concept:
We compare the number of beads right after some RB were added and after 56 YB were added
When 56 YB were added,
No BB was added
Hence,
The number of BB is an unchanged quantity
From the 2nd sentence,
The numerator of 2/5 represents the number of BB after some RB was added
From the 3rd sentence,
The numerator of 2/9 represents the number of BB after 56 YB were added
Hence, equalise the numerators
However, the numerators are already the same
Hence,
2/5 of total (after RB added)
= 2/9 of total in the end
BB = 2u
Total (after RB added) = 5u
Total in the end = 9u
In this comparison,
The diff in the total number of beads is due to the addition of 56 YB
Hence,
9u - 5u = 56
4u = 56
1u = 56 ÷ 4
= 14
Since there were only RB and BB before adding 56 YB,
RB (after RB added)
= Total (after RB added) - BB
= 5u - 2u
= 3u
= 3 x 14
= 42
From the 1st sentence,
There were 9 RB at first
Hence,
RB added
= RB (after RB added) - RB at first
= 42 - 9
= 33 (Ans)
Start with 9 beads, add 33 red beads, new total is 42. If 2/5 of total beads are blue beads, which is 16.8? How does the beads have fractional number?
Then take 42 and add 56 yellows, new total is 98. 2/9 is blue, so blue beads are 21.778? Wrong answer again? The amount of blue beads don't match?
Brenda Tan
I like this video 😊. Do more psle videos please
This just proves that as we age, PSLE math becomes really redundant to actual working or adult life xD
your comment just proves why you failed PSLE math =)
It's all around you: mortgages, currency conversions, proportions, etc.
I tot it's worth highlighting.. while it may seem like the current employment situation favor skills/experience over educational qualification, plus thrs underemployment issues as well (at least frm my own personal employment experience), clearly those aren't the valid reasons for people to discount the efforts of learning and the importance of the subject.. if all employers and employees think this way, the society is set to fail.. Such dangerous mentality shld be discouraged at all costs.
Good edit
The Arithmetic guy looks 99% like Kaye (Bhumibhat Thavornsiri) from "Girl from Nowhere".
The answer to the Red and Blue beads question:
61 Red beads were added, but the question is WRONG.
Start off with 9 beads (Red & Blue)
Add 61 Red beads, total is now 70 beads, 2/5 are Blue beads (28 Blue beads)
Add 56 Yellow beads to the 70 beads, total is now 126 beads, 2/9 are Blue beads (also 28 Blue Beads)
The method to find the unknown of Red beads added:
Where x is the number of Red beads added,
we also know that Blue beads remain constant,
Blue beads is 2/5 * (9+x)
Blue beads is also 2/9 * (9+56+x)
2/5 * (9+x) = 2/9 * (65+x)
Solving x:
8x=488
x=61 (Red beads added)
61 Red beads were added.
But we started with 9 beads only, how did we have 28 Blue beads?
salute the guy with smart mental cal, cn try compete with ms munchie.. as for the guy majoring in econs who dk math modeling and basic math, hmm maybe he is either jus too stressed in front of camera or doing it on purpose for entertainment.. if not, rlly doesn't do any justice to the rest of us who scored A too
All along have A*
I wan hire the editor
I always thought Australians were the ones who shorten terms, but Singaporeans too? PSLE is a new one. In Australia, we just say primary school level.
is psle score inflated ? i got 174 and i took CS
No, most people that went to NUS with high A level scores happens to be ip students from top JCs
The black T shirt guy not so intelligent. Sad
First