Problem Solving

A Semicircle is divided into 8 portions and has the points O to W. The semi circle has the length of 1 mile and a man starts at O travelling at 15 mph. In between what points will the man be after 3 minutes?

A. Q to R B. R to S C. S to T D. T to U E. U to V

it should be E

The circumference of the semicircle is (pi*r), which equals (pi*1/2) miles. Assuming pi=3. the distance comes to a little over 1.5 miles.
In 3 min the person would be covering a little over 3/4th of a mile (0.75 mile). This distance will be a little less than half of the distance calculated. hence the answer should be "B"; R to S.

the semicircle has a length of 1 mile and it is divided into 8 equal parts.So each part will equal to 1/8=0.125 mile
The speed of the man is 15mph.
Thus in 60 minutes it goes 15 miles.
Hence in 3 minutes it will go (15/60)*3=0.75 miles
If OP=0.125,OQ=0.250,OR=0.375,OS=0.5,OT=0.625,OU=0.750
So at 3 minutes,he will be at point U
=>After 3 minutes he will be between U and V,that is option E

one question: what does the length of semicircle mean?

1. is it pi*r ?
2. or is it (pi*r+diameter) ?

I have assumed that length means circumference of the semicircle = 1 mile
8 equal partitions are
o-p,p-q,q-r,r-s,s-t ,t-u,u-v,v-w
Now each is equal to 1/8 of a mile.

to cover one of the partitions it will take 1/8/(15) = 60/8*15 = 4/8 = 1/2 minute
time taken to cover o-p = 1/2
p-q =1/2 (total time =1)
q-r = 1/2 (total time =1.5)
r-s= 1/2 (total time = 2.0)
s-t = 1/2(total time = 2.5)
t-u = 1/2(total time = 3.0)
u-v (person will be here at the starting point that is u) (E)
v-w

ern5231 wrote:A Semicircle is divided into 8 portions and has the points O to W. The semi circle has the length of 1 mile and a man starts at O travelling at 15 mph. In between what points will the man be after 3 minutes?

A. Q to R B. R to S C. S to T D. T to U E. U to V

Hi,

I'm not sure from where you got this problem, but you'll never see something this poorly worded in the GMAT.

First, what does "length" of the semi-circle mean? Circumference of the arc? Diameter? Radius? Circumference of the arc plus the diameter?

Second, nowhere does it say that the 8 portions are equal or where the points are located; are they all located on the arc? Are some of them located on the diameter?

Without clarification, there's no way to answer the question.

What's the source of the question?

Hey stuart,

I totally agree, and that is the reason i am highly confused. I have got this from a friend of mine. Maybe its incorrect.

Thanks anyways.