Problem Solving

Charles , a novice skier , skis downhill at 8 miles per hour. He is passed by Kiko , an experienced skier at 60 miles per hour . Exactly 1 mile after passing Charles , Kiko falls and stops . How many minutes after the fall will Charles reach Kiko ?

a. 5.5
b. 6
c . 6.5
d . 7
e . 7.5

IMO E

We just need to calculate the time required by charles to cover a mile.

R T D

8 t 1

t=1/8 = 7.5/60

7.5 minutes.

bblast wrote:IMO E

We just need to calculate the time required by charles to cover a mile.

R T D

8 t 1

t=1/8 = 7.5/60

7.5 minutes.

I did the same mistake by choosing 7.5 ,which is incorrect

OA C

And I am unable to guesstimate the reason.

Oh

The only thing I can work out here is as follows :

r t d for kiko

60 t 1

therefore

t=1/60 hrs = 1 min.

Now the 7.5 minutes which charles travels also includes the 1 minute for Kiko's travel.(as charles has not stopped when Kiko overtook him)

But we are being asked as to how much time after Kiko's fall charles reached the point, hence Kiko had travelled 1 minute and charles also 1 minute(covering some disctance) by the time kiko fell.

additional time travelled by charles = 7.5-1
= 6.5

woof tricky one. Good one infact

whats the source ?

While Kiko was reaching the point, Charles did covered a certain distance.

1] We know that Charles crashed 1 minute after he passed Kiko (60 miles/ hour = 1 miles / min)

We can determine the distance between Charles and Kiko at the moment of the crash with this function:

2] (60 m/h - 8 m/h) / 60 minutes * 1 minute

<=>52/60 * 1 minute = 0,8666 miles.

Since Charles is now immobile, we have to estimate how long it will take for Kiko to arrive on the crash zone:

3] We know Kiko travel at 8 miles/ hour that is to say 0,1333 miles/ minute.

Then, it will takes 0,86666 miles / 0,13333 miles(per minute) = 6,6 mins for Kiko to arrive on the crash zone

Answer C (but it is curious that it is not exactly the proposed answer)

(My apologizes for my poor english)

bblast wrote:woof tricky one. Good one infact

whats the source ?

Source - Powerscore

Deepthi Subbu wrote:

bblast wrote:woof tricky one. Good one infact

whats the source ?

Source - Powerscore

i think my solution is correct Deepthi.

any more such questions ??, very gmat like i say.

bblast wrote:

Deepthi Subbu wrote:

bblast wrote:woof tricky one. Good one infact

whats the source ?

Source - Powerscore

i think my solution is correct Deepthi.

any more such questions ??, very gmat like i say.

Oh yes , your method is indeed correct

I'l post more of such questions if I find them .

Deepthi Subbu wrote:Charles , a novice skier , skis downhill at 8 miles per hour. He is passed by Kiko , an experienced skier at 60 miles per hour . Exactly 1 mile after passing Charles , Kiko falls and stops . How many minutes after the fall will Charles reach Kiko ?

a. 5.5
b. 6
c . 6.5
d . 7
e . 7.5

Hi there,

How many minutes each one needs to run 1 mile?

> Kiko needs 1 mile / 60 mph = 1/60 h = 1 min
> Charles needs 1 mile / 8 mph = 1/8 h = 60/8 min = 7.5 min

The answer is therefore 6.5min, because Charles "used" the 1 min Kiko run till he (Kiko) fall!

Regards,
Fabio.