Q&A - PSLE Math

[MathIzzzFun]

Ngserene617:

Winx5015:

MathIzzzFun



:thankyou:

Hi, pls help on these questions:

1. Malcom's salary in January was $2800. He saved 3/8 of it. In February, his salary increased by 25% and he saved 35% of it. What was the percentage increase in Malcom's savings from January to February? ( Give your answer to the nearest 1%)

Thanks

Hi
Q1.

http://i39.tinypic.com/119w95f.jpg\">

cheers.

[MathIzzzFun]

Ngserene617:

Winx5015:

MathIzzzFun



:thankyou:

Hi, pls help on these questions:


2. Ms Sumei spent $672 of her savings on clothing and 3/8 of the remainder on cosmetics. She had 1/4 of her savings left. What was Ms Sumei's original amount of savings?

Thanks

Hi

Remainder after spending $672 --> 8 units
Cosmetics --> 3 units
1/4 of savings --> 5 units
Total savings --> 20 units
Clothing --> 20 units - 8 units = 12 units
12 units --> $ 672
Original savings --> 20/12 x $ 672 = $ 1120

cheers.

[jewelbox]

Hi, appreciate help on the following qns :


1. Four children Min, Nathan, Tom and Caleb each have some savings. The amount of money Nathan has is 1/3 of the total amount of money Tom, Min and Caleb have. The amount of money Tom has is 1/4 of the total amount of money Nathan, Min and Caleb have. The amount of money Min has is 1/5 of the total amount of money Nathan, Tom and Caleb have. If Caleb saves $1035, how much do the four children have althogether? Ans $7200

2. At a carnival, there were 40% more males than females. There was an equal number of males without caps to the number of females without caps. The number of males with caps to the number of females with caps was 6:2.

a) What was the ratio of the number oof females with caps to the number of females without caps? Ans : 1:4

b) Midway, 800 females left the carnival. In the end, there were 3/7 as many females as males remaining behind. How many people were at the carnival at first? Ans : 4800

[tianzhu]

jewelbox:

Hi, appreciate help on the following qns :


1. Four children Min, Nathan, Tom and Caleb each have some savings. The amount of money Nathan has is 1/3 of the total amount of money Tom, Min and Caleb have. The amount of money Tom has is 1/4 of the total amount of money Nathan, Min and Caleb have. The amount of money Min has is 1/5 of the total amount of money Nathan, Tom and Caleb have. If Caleb saves $1035, how much do the four children have althogether? Ans $7200

Hi

This question was discussed before.

The total amount of money in the three scenarios is the same. Make the total number of units the same.

A common multiple of 4, 5 and 6 is 60.

Nat : (Tom + Min + Caleb) ------ 1:3 ((4) ------ 15:45 (60)
Tom : (Nat + Min + Caleb) ------ 1:4 (5) ------ 12:48 (60)
Min : (Nat + Tom + Caleb) ------ 1:5 (6) ------ 10:50 (60)

Nat ------ 15 units
Tom ------ 12 units
Min ------- 10 units
Caleb ------ 23 units

23 units ------ 1035
1 unit ------ 45

60*45 ------ 2700

Best wishes

[tianzhu]

jewelbox:

2. At a carnival, there were 40% more males than females. There was an equal number of males without caps to the number of females without caps. The number of males with caps to the number of females with caps was 6:2.

a) What was the ratio of the number oof females with caps to the number of females without caps? Ans : 1:4

b) Midway, 800 females left the carnival. In the end, there were 3/7 as many females as males remaining behind. How many people were at the carnival at first? Ans : 4800

Hi

You may use MD or work using units.

Male ------- 14 units
Females ------ 10 units

8 units (males w/o caps) + 6 units (males with caps)
8 units (females w/o caps) + 2 units (females with caps)

The ratio of the number of females with caps to the number of females without caps ----- 2:8 ------ 1:4

At first
Female:Male ------ 10:14 ------ 5:7

In the end
Female:Male ------ 3:7

800 females left the carnival, the number of males remains the same before and after

2 units ----- 800
1 unit ------ 400

(5*400) + (7*400) ------- 4800 (number of people were at the carnival at first)

Best wishes

[jewelbox]

Thanks Tianzhu, you are fast. I will slowly digest your solutions. Meanwhile i have prob solving this qn. Thanks. http://i42.tinypic.com/zbp0o.jpg\">

http://i42.tinypic.com/2vx51tx.jpg\">

[atutor2001]

Answer for Q8 is :


Area of sector ABE - Area of triangle BCD
= (1/8 x 22/7 x 7 x 7) - (1/2 x 7 x 7/2)
=77/4 - 49/4 =28/4 = 7

[peggy]

Hi, my mind just isn’t working. This should be an easy one but probably I might have solved too difficult questions lately till I can’t solve the easy one. Please help.


2/3 of Ali’s story books was the same as 3/5 of Raju’s story books. If Ali had 100 fewer books, how many books would Ali have ?

[Zack7]

peggy:

Hi, my mind just isn't working. This should be an easy one but probably I might have solved too difficult questions lately till I can't solve the easy one. Please help.


2/3 of Ali's story books was the same as 3/5 of Raju's story books. If Ali had 100 fewer books, how many books would Ali have ?

2/3 x = 3/5y
Y-x = 100

Solving,

X=900

[Zack7]

jewelbox:

Thanks Tianzhu, you are fast. I will slowly digest your solutions. Meanwhile i have prob solving this qn. Thanks. http://i42.tinypic.com/zbp0o.jpg\">

http://i42.tinypic.com/2vx51tx.jpg\">

Q6

Let x be square area, y is rect area
Let z be area cutout

5x = 2y
Y-z = 3(x-z)

X is 36cm^2

So y is 90

Z is 9