Q&A - PSLE Math

[tianzhu]

parents222:

Please help with this speed question and many thanks in advance...


Amy and Betty ran in a race. When Amy has completed 7/8 of the distance, Betty had only completed 2/3 of the distance of the race.

Amy's average speed for the race was 80m/min faster than Betty's. What was Betty's average speed for the race in m/min?

Hi

As in any questions on Speed, it’s useful to start with a simple diagram.

A common multiple of 3 and 8 is 24

First consider the distance ratio.

Amy ------- 21 units
Betty ------ 16 units

Speed and distance are in direct proportion to each other.

Amy covered more distance than Betty during the same period; this means her speed is higher than Betty.

21 – 16 -------5

5 units ------- 80

1 unit -------- 16

Betty’s speed -------- 16*16 ------- 256 m/min

Best wishes

[parents222]

Hi tianzhu, now I understand and it seems simple too! Thank you very much for your time!!

[parents222]

Please help with this ratio question and many thanks in advance…


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 female with caps was 6:2.

a. What was the ratio of the number of females with caps to the number of females without caps?

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?

[tianzhu]

parents222:

Please help with this ratio question and many thanks in advance...


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 female with caps was 6:2.

a. What was the ratio of the number of females with caps to the number of females without caps?

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?

Hi

You may use MD or work using units.

Male ------- 14 units
Female ------ 10 units

The number of males with caps to the number of female with caps was 6:2.

Male (caps) ------- 6 units
Female (caps) ------- 2 units

Male (w/o caps) ------- 8 units
Female (w/o caps) ------- 8 units

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

The number of males remained the same.

Male -------- 14 units
Female ------- 6 units

4 units -------- 800
1 unit -------- 200

Number of people at the carnival at first ------- 24 units -------- 4800

Best wishes

[YumYum]

Hi, I need help with this Qn. thanks http://i50.tinypic.com/90ni9v.png\">

[YumYum]

Hi, can anyone pls help with this Qn?


Alicia gave some beads to Betty such that Betty had 40% of the beads that Alicia had. After that, Alicia gave another 170 beads to Betty. In the end, Betty had 80% of the number of beads that Alicia had. How many beads did Betty have in the end?

thanks.

thanks

[tianzhu]

YumYum:

Hi, I need help with this Qn. thanks http://i50.tinypic.com/90ni9v.png\">

Hi

Area of square ------ 28*28 -------- 784
Area of quadrant -------- 616

Area of (A+B) ------- 784-616 ------ 168

Area of semi circle -------- 308

A+B ------ 168
B+C ------ 308

A+B+B+C -------476

A+C ------ B+B

Hence

B+B+B+B -------476

B --------119

Best wishes

[tianzhu]

YumYum:

Hi, can anyone pls help with this Qn?


Alicia gave some beads to Betty such that Betty had 40% of the beads that Alicia had. After that, Alicia gave another 170 beads to Betty. In the end, Betty had 80% of the number of beads that Alicia had. How many beads did Betty have in the end?

thanks.

Hi

The total number of beads remained the same.

At first
Alicia: Betty ------- 5:2 (7) --------45:18 (63)

In the end
Alicia: Betty ------- 5:4 (9) --------35:28 (63)

10 units ------ 170

1 unit ------ 17

Betty ------ 28*17 -------476

Best wishes

[YumYum]

Hi Tianzhu,


thank you for the usual prompt help!

[tianzhu]

YumYum:

Hi Tianzhu,


thank you for the usual prompt help!

Hi

You're welcome.

Best wishes