Q&A - P5 Math

[Maths Hub]

YumYum:

Hi, need help with qn:


In may, the average number of participants in one pottery class was 24. In June, 5 new pottery classes were added. The average number of participants in all the pottery classes became 26. If there were 32 participants in each of the new pottery classes, find the total number of participants in all the pottery classes in June.

Thanks!

Total extra members from the new classes that contribute to the rise in old average --> (32 - 26) X 5 = 30
Rise in old average --> 26 - 24 = 2
Original number of classes --> 30 / 2 = 15
New number of classes --> 15 + 5 = 20
Total number of participants --> 20 X 26 = 520

Cheers.

[zombie]

This question is taken from Nanyang SA2, 2011 question 17 paper 2.

Can someone help me to solve ? Thanks !

At first, the ratio of the number of men to the number of women in a
cinema was 2:5. When 48 women and some men entered the cinema
the number of women increased by 12% and the total number of people
in the cinema increased by 20%.
(a) How many men were there at first?
(b) What percentage of the people in the cinema were men in the end?
Express your answer as a mixed number.

[dazzlego]

savoury sweet:

Hi everyone,kindly help to solve the following question. Thanks so much.


A grp of pupils claculated their average score for Science test. They noted that if anyone scored 14 marks and more, their average would be 90. If anyone scored 4 marks fewer, their average score would be 88. How many pupils are there in the grp?

Hi savoury sweet,

You can assume that the number of pupils is 1 unit
case 1: the total score -> 90 units - 14
case 2: the total score -> 88 units + 4
2 units -> 14 + 4 = 18
1 unit -> 18 ÷ 2 = 9

Cheers :celebrate:

[dazzlego]

zombie:

Hello, helping my son to solve using agebra,

can someone tell me if the answer is correct ?

Can someone suggest other method? i was taught using Algebra in the 1970s. lost touch. Thanks :roll:

Mrs Lim bought some green apples for an average cost of $0.45. However, if she exchanges 4 green apples for 4 red apples, which cost $0.75 each, the average price of each apple would be $0.55
How many apples are there altogether ?

Let the total number of apples be X
X (0.45)+ (4x 0.75) \t= 0.55 X
0.45 (X - 4) + 3.00\t= 0.55 X
0.45 X -18 + 3.00\t= 0.55 X - 0.45 X
1.2\t= 0.10 X
12\t= X
there are 12 apples altogether

Hi zombie,

Generally it is correct. However don't rush the steps and don't miss all the details (decimal points, the character (X) must be writen after the number, etc)
Let the total number of apples be X
0.45 (X - 4) + 4 x 0.75 \t= 0.55 X
0.45 (X - 4) + 3.00\t= 0.55 X
0.45 X - 1.80 + 3.00\t= 0.55 X
0.45 X + 1.20 = 0.55 X
1.20\t= 0.10 X
12\t= X
there are 12 apples altogether


Cheers :celebrate:

[papilion]

Can someone please help to solve the question posted by @zombie ?

[verykiasumummy]

i can try to help :


12% –> 48
1% –> 4
100% –> 400 (no of women at first)

5u –> 400
1u –> 80
2u –> 160 (no of men at first)

400 + 160 = 560 (total people at first)
120/100 x 560 = 672 (total people in the end)
672 - 560 = 112 (addn people)
112 - 48 = 64 (men added)
160 + 64 = 224 (men in the end)
224/672 x 100% = 33 1/3%

hope it helps…

[verykiasumummy]

btw, u should post ur question in the correct thread for prompt answers by the other experts here…

[Udon]

Hi hi… please to check is my calculation is correct?

Thanks for your help in advance…

Q1. All the water from the bottle is poured into a square-based container without spilling. The height of the container is 9 cm. What is the length of the container?

576 / 9 = 64cm ?

[verykiasumummy]

Udon:

Hi hi.. please to check is my calculation is correct?

Thanks for your help in advance...

Q1. All the water from the bottle is poured into a square-based container without spilling. The height of the container is 9 cm. What is the length of the container?

576 / 9 = 64cm ?

u should have 1 last step.

576 / 9 = 64cm2 (base area)

square root of 64 = 8cm (length of container)

ans : 8cm.

[Udon]

verykiasumummy:

Udon:

Hi hi.. please to check is my calculation is correct?

Thanks for your help in advance...

Q1. All the water from the bottle is poured into a square-based container without spilling. The height of the container is 9 cm. What is the length of the container?

576 / 9 = 64cm ?

u should have 1 last step.

576 / 9 = 64cm2 (base area)

square root of 64 = 8cm (length of container)

ans : 8cm.

oh....thanks