Q&A - P4 Math
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Mr Tan bought 5 kg of flour. He used 3/4 kg of it to bake some muffins and 7/8 kg of it to bake a cake. How much flour was left.
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hardeshis:
Mr Tan bought 5 kg of flour. He used 3/4 kg of it to bake some muffins and 7/8 kg of it to bake a cake. How much flour was left.
I think there must have been a typo error. 3/4 + 7/8 = more than 1. Probably the question reads and 7/8 of the remainder to bake a cake. -
Laura02:
ya may be..hardeshis:
Mr Tan bought 5 kg of flour. He used 3/4 kg of it to bake some muffins and 7/8 kg of it to bake a cake. How much flour was left.
I think there must have been a typo error. 3/4 + 7/8 = more than 1. Probably the question reads and 7/8 of the remainder to bake a cake. -
If 3 workers takes 6 days to complete painting a house, how many workers are needed if it needs 2 days to complete the job?
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ttyh:
If 3 workers takes 6 days to complete painting a house, how many workers are needed if it needs 2 days to complete the job?
Hi
There are a few approaches.
A neat way is the use compound units.
Number of worker days to paint a house -------- 3*6 ------- 18
If it is 2 days, number of workers ------- 18/2 ------- 9
Best wishes -
Hi needs help to understand the question. Thanks in advance
There are 80 pupils in class A and class B. 4/9 of pupils in class A are boys and 3/5 of the pupils in class B are girls.
a) How many pupils are there in class A?
b) How many boys are there in both classes?
Ans (a) 45 & (b) 34 -
little patrick:
4/9 of pupils in class A are boys --> number of pupils in class A is a multiple of 9Hi needs help to understand the question. Thanks in advance
There are 80 pupils in class A and class B. 4/9 of pupils in class A are boys and 3/5 of the pupils in class B are girls.
a) How many pupils are there in class A?
b) How many boys are there in both classes?
Ans (a) 45 & (b) 34
3/5 of the pupils in class B are girls --> number of pupils is a multiple of 5
Total number 80 is a multiple of 5 --> number of pupils in class A is ALSO a multiple of 5 ie number of pupils in class A is a multiple of 5 and 9.
Smallest multiple of 5 & 9 --> 45
Number of pupils in Class A --> 45
Number of pupils in Class B --> 35
..with these, I think you can work out (b)
cheers. -
MathIzzzFun:
Hi , tks for your explain but I'm still not very understand the part 2 -> Total numer 80 is a multiple of 5 ......
4/9 of pupils in class A are boys --> number of pupils in class A is a multiple of 9little patrick:
Hi needs help to understand the question. Thanks in advance
There are 80 pupils in class A and class B. 4/9 of pupils in class A are boys and 3/5 of the pupils in class B are girls.
a) How many pupils are there in class A?
b) How many boys are there in both classes?
Ans (a) 45 & (b) 34
3/5 of the pupils in class B are girls --> number of pupils is a multiple of 5
Total number 80 is a multiple of 5 --> number of pupils in class A is ALSO a multiple of 5 ie number of pupils in class A is a multiple of 5 and 9.
Smallest multiple of 5 & 9 --> 45
Number of pupils in Class A --> 45
Number of pupils in Class B --> 35
..with these, I think you can work out (b)
cheers.
if the question put in this way for (a) , find the number of pupils in Class B.
Does it means that I still need to find out the Class A number first 90-45=35 OR there is another way of finding the number of pupils in Class B without Class A number?
Tks
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little patrick:
Hi , tks for your explain but I'm still not very understand the part 2 -> Total numer 80 is a multiple of 5 ......
4/9 of pupils in class A are boys --> number of pupils in class A is a multiple of 9MathIzzzFun:
[quote=\"little patrick\"]Hi needs help to understand the question. Thanks in advance
There are 80 pupils in class A and class B. 4/9 of pupils in class A are boys and 3/5 of the pupils in class B are girls.
a) How many pupils are there in class A?
b) How many boys are there in both classes?
Ans (a) 45 & (b) 34
3/5 of the pupils in class B are girls --> number of pupils is a multiple of 5
Total number 80 is a multiple of 5 --> number of pupils in class A is ALSO a multiple of 5 ie number of pupils in class A is a multiple of 5 and 9.
Smallest multiple of 5 & 9 --> 45
Number of pupils in Class A --> 45
Number of pupils in Class B --> 35
..with these, I think you can work out (b)
cheers.
if the question put in this way for (a) , find the number of pupils in Class B.
Does it means that I still need to find out the Class A number first 90-45=35 OR there is another way of finding the number of pupils in Class B without Class A number?
Tks[/quote]There is no hard and fast rule how one work out the answer. If it is easier to solve for A, then solve for A first. If it is easier to solve for B then solve for B first.
In this case, it is quite straightforward to solve for A, so get A first and then B, even if the question asks for B.
80 = 16 x 5 --> suppose there are 16 packets containing 5 sweets each.
After giving away 4 packets, how many sweets are left ?
16-4 = 12 packets --> sweets left = 12 x 5 --> multiple of 5
So, if I remove any multiple of 5 from 80, the remainder will also be a multiple of 5.
Number A + Number B = Number C
If number A and number C is a multiple of 5, then Number B must also be a multiple of 5
cheers. -
how to do:
the number of $5 notes tat gopal has is 1/3 the numbr of $2 notes. the number of $10 notes is 1/2 the number of $2 notes. aft spendg all the $10 notes and 2/3 of the $2 notes, gopal has $210 left. how much did she spend altogether?
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