Q&A - PSLE Math

[stary]

Hi all,


Have 2 questions that I need help with…

1.
A and B start cycling at the same time from the same place.
If they cycle in the opposite direction, they will be 37 2/5 km apart after 55 min.
If they cycle in the same direction, A will be 2 1/5 km ahead of B after 55 min.
(a) Find the diff. in their average speed.
(b) Find the average speed of the slower cyclist.(Express in decimals)

2.
At 2pm, Melvin started from Vivo City and travelled towards Sun City at an average speed of 78km/h. At 3:12pm, he went past Andrew who was travelling from Sun City to Vivo City. At 3:42pm, the distance between Melvin and Andrew was 75 km.
(a) What was Andrew’s speed?
(b) At what time did Andrew reach Vivi City?


Your help is GREATLY appreciated by me.

Best regards,
Stary

[raghupavithra]

Mr Hambali is 39 years 4 months old.his son is 1/3 as old as he.How old is his son?

(Give your answer in years)

how to do this sum

[raghupavithra]

Mr sim earns $2500 every month.After giving 3/5 of his salary to his wife and 1/2 of the remainder to his son, he saves the rest. How much money can Mr sim save in 3 years?

[bobsg01]

Primary 6 Problem.


Thanks for your kind help.

http://i53.tinypic.com/2vceyvk.jpg\">

[corneyAmber]

raghupavithra:

Mr Hambali is 39 years 4 months old.his son is 1/3 as old as he.How old is his son?

(Give your answer in years)

how to do this sum

Father's age in months = 468+4 = 472
Son age = 1/3 *472 = 472/3 in months
Son's age in years
= 472/(3*12) = 13 1/9 years

[corneyAmber]

raghupavithra:

Mr sim earns $2500 every month.After giving 3/5 of his salary to his wife and 1/2 of the remainder to his son, he saves the rest. How much money can Mr sim save in 3 years?

Amount left after giving wife per month
= 2/5 * 2500
= 1000

After giving 1/2 of remainder to son, amt he saves per month = 1000-500 = 500

Hence savings in 3 years = 36*500 = $18,000

[corneyAmber]

bobsg01:

Primary 6 Problem.


Thanks for your kind help.

http://i53.tinypic.com/2vceyvk.jpg\">

1 litre = 1000 cubic cm
5.95 litres = 1000 x 5.95 = 5950 cubic cm

(a) Water level = 5950/700 = 8.5cm

(b) Remaining level to full = 10-8.5 =1.5cm

hence amount of water to fill tank = 700 x 1.5 = 1050 cubic cm or 1.05 litres

[stary]

Can somebody help me???...

[stary]

Wow... Since 18 May 2008, we've reached the 346th page!!!

Keep it up team! :rahrah: :rahrah: :rahrah:

[corneyAmber]

stary:

Hi all,


Have 2 questions that I need help with...

1.
A and B start cycling at the same time from the same place.
If they cycle in the opposite direction, they will be 37 2/5 km apart after 55 min.
If they cycle in the same direction, A will be 2 1/5 km ahead of B after 55 min.
(a) Find the diff. in their average speed.
(b) Find the average speed of the slower cyclist.(Express in decimals)

Your help is GREATLY appreciated by me.

Best regards,
Stary

A <--------------------|------------> B

A |-------------------->
B |------------->

So whether they go the same or opposite direction,
difference in distance = 2 1/5km
time taken = 55/60 h
(a) difference in average speed
= dist/time
= 11/5 x 60/55
= 2.4 km/h

(b) distance covered by slower cyclist
= (37 2/5 - 2 1/5) / 2
= 176/10 km
Hence average speed of slower cyclist
= 176/10 x 60/55
= 19.2 km/h