Tutor MathsGuru: Ask me for your burning Maths questions!

[Almighty]

Hi Vaniila cake,


Wish i had a Big sister like u!!! I hv a dobt reg yr answer for this problem:
\"Wei Qiang walked up a flight of steps at an average speed of 50 m/min.
When he reached the top, he ran down the same flight of steps at a speed of 200 m/min. If he took a total of 1 min to walk up and run down, how many seconds did he take to walk up the flight of steps ?\"

Ratio of time
4 : 1
Multiply by 4( Must be by 12 right? )
48 : 12

(48+12)min= 60 min ie he took a total of 1 min to walk up and run down
5u = 60 seconds
(I dint get how u interpretated 60 min n then say 1 min .I think it sh b (48 + 12) Secs = 60 Secs= 1min.But how can it b (48+12) secs as ratio of time in 4:1 is in min.
Can u please clarify?

[CoffeeCat]

almighty, I think it’s just a typo. What she meant is using the ratio of time, wei qiang will took 48 secs to walk up and 12 secs to run down. The units are not crucial because ratios are dimensionless.

[Vanilla Cake]

CoffeeCat:

almighty, I think it's just a typo. What she meant is using the ratio of time, wei qiang will took 48 secs to walk up and 12 secs to run down. The units are not crucial because ratios are dimensionless.

Thanks, CoffeeCat.


Hi Almightly,
I have revised the workings to make it clear.Was in a rush and didn't check thoroughly.

[Almighty]

Hi vanilla cake,

Thanks for your reply.But my doubt was, Ratio of time is in min or seconds?Since the question says:average speed of 50 m/min and 200 m/min.I did the Ratio of time in minutes and got stuck.Pl clarify how u made ratio of time in secs.

[Tang]

Almighty:

Hi vanilla cake,

Thanks for your reply.But my doubt was, Ratio of time is in min or seconds?Since the question says:average speed of 50 m/min and 200 m/min.I did the Ratio of time in minutes and got stuck.Pl clarify how u made ratio of time in secs.

Ratio has no unit.

But when comparing Ratio, the units of each term must be the same.

[Almighty]

Thank you Tang.This is a new one i learnt 2day.This concept was not known 2 me until now.Thank you to all.

[Tang]

Almighty:

Thank you Tang.This is a new one i learnt 2day.This concept was not known 2 me until now.Thank you to all.

Always compare apple to apple.

[RedRedWine]

Hi Maths Guru


I have 2 questions from Catholic High Prelim exan 2. Can you help tp solve?

1) At a swimmimg pool, the number of boys to the numbers of girls was 4:3. After 3/8 of the boys left and 12 more girls joined the group, there were 2/3 as many boys as girls. How many children were there at the swimming pool first?

2) Tom had $144 more than Ali at first. After Tom spent 25% of his money and Ali spent 1/3 of his money. Tom had $122 more than Ali. How much did Tom have at first?

TIA

[MOE Hater]

RedRedWine:

Hi Maths Guru


I have 2 questions from Catholic High Prelim exan 2. Can you help tp solve?

1) At a swimmimg pool, the number of boys to the numbers of girls was 4:3. After 3/8 of the boys left and 12 more girls joined the group, there were 2/3 as many boys as girls. How many children were there at the swimming pool first?

2) Tom had $144 more than Ali at first. After Tom spent 25% of his money and Ali spent 1/3 of his money. Tom had $122 more than Ali. How much did Tom have at first?

TIA

1) At First - Boys : Girls = 4 : 3 = 16 : 12
After Boys Left - Boys : Girls = 5/8 x 16 : 12 = 10 : 12
After Girls Joined - Boys : Girls = 10 : 3/2 x 10 = 10 : 15
(15-12)u = 3u = 12
1u = 12/3 = 4
(16+12)u = 28u = 4 x 28 = 112

2) Let x be the money Tom had at first

(1-25/100)x = (1-1/3)(x-144) + 122
3/4 x = 2/3 x - 96 + 122
9/12 x = 8/12 x + 26
1/12 x = 26
x = 312

Hope this is self-explanatory enough. :lol:

[abc_parent]

Hi MOE HAter, VanillaCake & Maths Monster

Thanks for your help.

Vanilla Cake, I have indicated the exam paper name in my Subject already, thanks for your pointer, though!