Q&A - PSLE Math

[Ender]

Can anyone help?

There were 275 boxes of cookies and muffin in a bakery. Then 70% of the boxes of cookies and 60% of the boxes of muffin were sold. The ratio of the number of boxes of cookies left to the number of boxes of muffins left was 2:1.

a) How many boxes of cookies and muffins were left?
b) How many boxes of muffins were in the bakery at first?

Work backwards.


In the end,
C : M = > 24 (30%) : 12 (40%)

In the beginning,
C : M = > 80 : 30

80u + 30u = 275
110u=275
u=2.5

a) Muffin + Cookies left = 36u = 90 boxes
b) Muffin at first = 30u = 75 boxes

[Sruthi]

please help with this question.thank you

[Daddy]

Hi all, need help on these questions.

[Sruthi]

please help with this question. Thank you in advance

[Whitearies]

[Whitearies]

[pirate]

A car and lorry which were 75 km apart started to travel towards each other at the same time . The car 35 km/h faster than the lorry. They went past each other after 2/5 hours.

a) How far the lorry travel when it pass the car?
b) Find the speed of lorry


Need help with this question. Thank you.

In 2/5 hours, car would have travelled 35*2/5 = 14 km more than lorry.

(a) Distance travelled by lorry in 2/5 hours = (75 - 14)/2 = 30.5 km
(b) Speed of lorry = 30.5km/(2/5 h) = 30.5*5/2 = 76.25 km/h

[pirate]

(a) Mrs Ting travelled 500m + 500m = 1km further than Mdm Leela (Mdm Leela travelled 500m less than the bank, Mrs Ting travelled 500m further than the bank).

(b) Since Madam Leela travelled at 10km/h slower than Mrs Ting, amount of time travelled so that Mrs Ting travels 1km more than Mdm Leela is 1 / 10 = 1/10 hour.

Distance of Madam Leela's house from the bank is therefore (1/10h * 55km/h) + 0.5km = 6 km

[pirate]

This is similar in concept to the car/lorry and Mrs Ting/Mdm Leela questions.

Cost of calculators = $(68.40 - 32.40) / 2 = $18
Price of calculators before discount = $18 / (1 - 0.25) = $18 / (0.75) = $24
Discount on calculators = $24 - $18 = $6

(a) Savings on pens = $18.60 - $6 = $12.60

(b) Discount percentage on pens = 12.60 / (12.60 + 18 + 32.40) * 100% = 12.60 / 63 * 100% = 20%

The number of pens and calculators bought are red herrings.

[pirate]

Can anyone help?

There were 275 boxes of cookies and muffin in a bakery. Then 70% of the boxes of cookies and 60% of the boxes of muffin were sold. The ratio of the number of boxes of cookies left to the number of boxes of muffins left was 2:1.

a) How many boxes of cookies and muffins were left?
b) How many boxes of muffins were in the bakery at first?

Let x be the number of boxes of cookies and y be the number of boxes of muffins,

100%-70%=30%
30%*x=[3x/10]
100%-60%=40%
40%*y=[4y/10]
[4y/10]*2=[8y/10]
[3x/10]=[8y/10]
3x=8y
x+y=275
275-y=x
3(275-y)=8y
825-3y=8y
825=11y
75=y
275-75=200
200=x
200*30%=60
75*40%=30
30+60=90
a)90
b)75

Hope this helps you.

Note: Those in [] means it is a fraction so as not to confuse you.

0.3c / 0.4m = 2 / 1
c / m = (2 * 0.4) / (1 * 0.3)
c / m = 0.8 / 0.3
c / m = 8 / 3

There were 8 units of cookies and 3 units of muffins = total 11 units at first
Each unit = 275 / 11 = 25 boxes

(b) there were 3 * 25 = 75 boxes of muffins at first

(a) there were 0.3 * 8 * 25 = 60 boxes of cookies left and 0.4 * 3 * 25 = 30 boxes of muffins left. (No idea whether the question was asking for no. of boxes of cookies left and no. of boxes of muffins left separately or no. of boxes of cookies and muffins left altogether.