Q&A - PSLE Math

[tianzhu]

Chan09:

Need help

There were twice as many red pens as blue pens.he sold the pens in bundles of 2 red and 3 blue.
After selling all the blue pens, he still had 120 red pens left. How many penns did he have at first?
Ans: 270

Hi

You may use MD or UM.

Red : Blue ------ 2:1 -------- 6:3

He sold 2 units of red pens and 3 units of blue pens.

Hence, 4 units ------ 120

This gives 1 unit ------ 30

Number of pen@first ------ 9 units ------- 270

Best wishes

[isetan]

Hi, need help to cross check the ans to this question:


Two boxes, A and B, contain some red and blue beads. In box A, the ratio of the no. Of red beads to the no. of blue beads is 2:1. In box B, the ratio of the no. Of red beads to blue beads is 1:3. Box A has thrice as many beads as Box B.

A) find the ratio of the no. of Red beads in box A to the no. of blue beads in box B.

B) if 105 red beads are taken out from box A and placed in box B, the ratio of the no. of the red beads to the no. of blue beads in box B becomes 3:2. What is the total no. of beads in the 2 boxes?

Our working leads ans A is – 8:1, ans B is – 480.

Appreciate anyone helps if the ans is correct. Many thanks.

[isetan]

Hi, another question:


Tan, Lim and Wong had some pens to sell. Tan had the least no. of pens. Wong’s no. of pens was 30% less than Lim’s. After Tan and Lim had each sold 50% of their pens, Lim had 95 more pens than Tan. If the three men had a total of 330 pens left, what is the total no. of pens they had at first?

[ksoh3000]

tks

[2cor41618]

isetan:

Hi, need help to cross check the ans to this question:


Two boxes, A and B, contain some red and blue beads. In box A, the ratio of the no. Of red beads to the no. of blue beads is 2:1. In box B, the ratio of the no. Of red beads to blue beads is 1:3. Box A has thrice as many beads as Box B.

A) find the ratio of the no. of Red beads in box A to the no. of blue beads in box B.

B) if 105 red beads are taken out from box A and placed in box B, the ratio of the no. of the red beads to the no. of blue beads in box B becomes 3:2. What is the total no. of beads in the 2 boxes?

Our working leads ans A is -- 8:1, ans B is -- 480.

Appreciate anyone helps if the ans is correct. Many thanks.

I think he answer to part a should be 8:3. Part b is correct

[2cor41618]

isetan:

Hi, another question:


Tan, Lim and Wong had some pens to sell. Tan had the least no. of pens. Wong's no. of pens was 30% less than Lim's. After Tan and Lim had each sold 50% of their pens, Lim had 95 more pens than Tan. If the three men had a total of 330 pens left, what is the total no. of pens they had at first?

At first

Wong---70%
Lim---100%

After T and L sold 1/2 of their share,

Lim---50%
Tan---95 less than 50%
Wong---70%

Thus, 50% + 50% + 70% ----330+ 95
170%---425 (Wong + Lim at first)
1%----2.5
Tan---2x ( 50 x 2.5 - 95) = 60

Total at first----60 + 425 = 485

[tutorsg_punggol]

ksoh3000:

tks

U're welcome! Hope it's not too difficult to understand.

[tamunawara]

thanks a lot . that was really useful

[tamunawara]

thanks a lot . that was really useful

[brastilava]

Hi, please help in this question:


Tin A, Tin B and Tin C are required to paint a complete wall. If only Tin A is used, we are short of 7 litres. If only Tin B is used, we are short of 5 litres. If only tin C is used, we are short of 3 litres. How many litres of paint is required to paint a complete wall?