Q&A - PSLE Math

[Winx5015]

Need help for the following questions.


(1). Alex left Town P at 7.30am and travelled towards Town Q. Jia Hao left Town Q at 8am and travelled towards Town P along the same road. Jia Hao’s average speed was 10 1/2 km/h faster than Alex’s average speed and he reached Town P at 12 noon while Alex was still 6km from Town Q.
(a). What was the distance between the 2 towns?
(b). At what time did Alex reach Town Q?

(2). Candle A and Candle B are of the same length. Candle A,which is broader, can burn for 5h while Candle B, the thinner candle, can burn for 4h. If both candles are lighted at the same time, how long does it take for Candle A to be twice as long left as Candle B?

Thanks!

[MathIzzzFun]

Winx5015:

Need help for the following questions.


(1). Alex left Town P at 7.30am and travelled towards Town Q. Jia Hao left Town Q at 8am and travelled towards Town P along the same road. Jia Hao's average speed was 10 1/2 km/h faster than Alex's average speed and he reached Town P at 12 noon while Alex was still 6km from Town Q.
(a). What was the distance between the 2 towns?
(b). At what time did Alex reach Town Q?

(2). Candle A and Candle B are of the same length. Candle A,which is broader, can burn for 5h while Candle B, the thinner candle, can burn for 4h. If both candles are lighted at the same time, how long does it take for Candle A to be twice as long left as Candle B?

Thanks!

Hi

Q2 .. I think this was discussed some time ago.. this is a speed question in disguise

In the same period of time, the length burned off Candle A to length burned off Candle B --> 4 : 5

http://www.flickr.com/photos/62167097@N02/6895397206/



cheers.

[MathIzzzFun]

Winx5015:

Need help for the following questions.


(1). Alex left Town P at 7.30am and travelled towards Town Q. Jia Hao left Town Q at 8am and travelled towards Town P along the same road. Jia Hao's average speed was 10 1/2 km/h faster than Alex's average speed and he reached Town P at 12 noon while Alex was still 6km from Town Q.
(a). What was the distance between the 2 towns?
(b). At what time did Alex reach Town Q?



Thanks!

Hi

Draw a diagram so that you can visualize the parts of journey involved.

Total time taken by Jia Hao to travel from Q to P = 4h
Extra distance travelled by Jia Hao = 4 x 10.5 = 42km

When Jia Hao started at 8am, Alex has travelled for 1/2 h --> \"headstart\"
so, \"head start\" + 6 km = 42 km
\"head start\" --> 36 km --> distance covered in 1/2 h by Alex
Alex's speed --> 72 km/h
Distance between P & Q = 72 km x 4 + 42 km = 330 km

At 12noon, Alex was still 6 km from Town Q,
6 / 72 = 1/6 h = 10 min

Alex will reach Town Q at 12.10pm

cheers.

[Zack7]

lousymum:

pls help


kumar had 50% more bookmarks than leon.
max had 75% as many bookmarks as kumar.
kumar and leon gave max a number of bookmarks in the ratio 3:1.
as a result, maz had twice as many bookmakrs as before, and leon had 16 bookmarks more than kumar.
how many bookmarks did kumar give to max?

tia

hi lousymum, if i may say, for whatever reasons, i don't think you are lousy as a mum. the fact that you care for your son or daughter shows that you aren't as lousy as you think you are.

let k be kumar bookmarks

le the number of bookmarks leon gave be x

so

kumar = k
leon = (2/3)k
max = 0.75k

so after giving, leon had 16 more than kumar

(2/3 k - x) - (k - 3x) = 16 ---- equation 1

so after giving, max had twice as many as before

0.75k = 4x

solving,

k = (16/3)x

sub into equation 1

32/9 x - x - 16/3 x + 3x = 16

2/9x = 16
x =72
k= 384

so how many bookmarks did kumar give to max? = 3x = 216

[MathIzzzFun]

lousymum:

pls help


kumar had 50% more bookmarks than leon.
max had 75% as many bookmarks as kumar.
kumar and leon gave max a number of bookmarks in the ratio 3:1.
as a result, max had twice as many bookmarks as before, and leon had 16 bookmarks more than kumar.
how many bookmarks did kumar give to max?

tia

Hi

Kumar:Leon --> 3:2
Kumar:Max --> 4:3
Kumar : Leon : Max --> 12 : 8 : 9 --> 48u : 32u : 36u

Max received a total of 36u of bookmarks from Kumar & Leon in ratio of 3:1,
Bookmarks given by Kumar : Leon --> 27u : 9u
Bookmarks left, Kumar : Leon --> 21u : 23u
2u --> 16, 1u --> 8

Bookmarks given by Kumar to Max --> 8 x 27 = 216

cheers.

[Winx5015]

MathIzzzFun


:thankyou:

[Zack7]

MathIzzzFun:

lousymum:

pls help


kumar had 50% more bookmarks than leon.
max had 75% as many bookmarks as kumar.
kumar and leon gave max a number of bookmarks in the ratio 3:1.
as a result, max had twice as many bookmarks as before, and leon had 16 bookmarks more than kumar.
how many bookmarks did kumar give to max?

tia

Hi

Kumar:Leon --> 3:2
Kumar:Max --> 4:3
Kumar : Leon : Max --> 12 : 8 : 9 --> 48u : 32u : 36u

Max received a total of 36u of bookmarks from Kumar & Leon in ratio of 3:1,
Bookmarks given by Kumar : Leon --> 27u : 9u
Bookmarks left, Kumar : Leon --> 21u : 23u
2u --> 16, 1u --> 8

Bookmarks given by Kumar to Max --> 8 x 27 = 216

cheers.

short simple sweet :goodpost:

[mathnoobs]

MathIzzzFun:

lousymum:

pls help


kumar had 50% more bookmarks than leon.
max had 75% as many bookmarks as kumar.
kumar and leon gave max a number of bookmarks in the ratio 3:1.
as a result, max had twice as many bookmarks as before, and leon had 16 bookmarks more than kumar.
how many bookmarks did kumar give to max?

tia

Hi

Kumar:Leon --> 3:2
Kumar:Max --> 4:3
Kumar : Leon : Max --> 12 : 8 : 9 --> 48u : 32u : 36u

Max received a total of 36u of bookmarks from Kumar & Leon in ratio of 3:1,
Bookmarks given by Kumar : Leon --> 27u : 9u
Bookmarks left, Kumar : Leon --> 21u : 23u
2u --> 16, 1u --> 8

Bookmarks given by Kumar to Max --> 8 x 27 = 216

cheers.

I'm afraid this is very deep for me. How do I know that I have to multiply 12:8:9 by 4 ? also how do I know that I have to multiply 3:1 by 9 ?

[mathnoobs]

mathnoobs:

MathIzzzFun:

[quote=\"lousymum\"]pls help


kumar had 50% more bookmarks than leon.
max had 75% as many bookmarks as kumar.
kumar and leon gave max a number of bookmarks in the ratio 3:1.
as a result, max had twice as many bookmarks as before, and leon had 16 bookmarks more than kumar.
how many bookmarks did kumar give to max?

tia

Hi

Kumar:Leon --> 3:2
Kumar:Max --> 4:3
Kumar : Leon : Max --> 12 : 8 : 9 --> 48u : 32u : 36u

Max received a total of 36u of bookmarks from Kumar & Leon in ratio of 3:1,
Bookmarks given by Kumar : Leon --> 27u : 9u
Bookmarks left, Kumar : Leon --> 21u : 23u
2u --> 16, 1u --> 8

Bookmarks given by Kumar to Max --> 8 x 27 = 216

cheers.

I'm afraid this is very deep for me. How do I know that I have to multiply 12:8:9 by 4 ? also how do I know that I have to multiply 3:1 by 9 ?[/quote]never mind. I finally figured it out. Still very deep though.

[Zack7]

mathnoobs:

MathIzzzFun:

[quote=\"lousymum\"]pls help


kumar had 50% more bookmarks than leon.
max had 75% as many bookmarks as kumar.
kumar and leon gave max a number of bookmarks in the ratio 3:1.
as a result, max had twice as many bookmarks as before, and leon had 16 bookmarks more than kumar.
how many bookmarks did kumar give to max?

tia

Hi

Kumar:Leon --> 3:2
Kumar:Max --> 4:3
Kumar : Leon : Max --> 12 : 8 : 9 --> 48u : 32u : 36u

Max received a total of 36u of bookmarks from Kumar & Leon in ratio of 3:1,
Bookmarks given by Kumar : Leon --> 27u : 9u
Bookmarks left, Kumar : Leon --> 21u : 23u
2u --> 16, 1u --> 8

Bookmarks given by Kumar to Max --> 8 x 27 = 216

cheers.

I'm afraid this is very deep for me. How do I know that I have to multiply 12:8:9 by 4 ? also how do I know that I have to multiply 3:1 by 9 ?[/quote]
Ratios are about scaling. You don't have to multiply them, just that u will b working with fractions.