20 mile course

[quocbao]

On a 20 mile course, Pat bicycled at an avg rate of 39 miles / h for the first 12 min and , without a break, ran the rest of the distance at an avg rat of 8 miles / h. How many minutes did Pat take to cover the entire course ?

A. 75
B. 105
C. 117
D. 150
E. 162

OA is C

Is there an easy way to solve this problem without a lot of calculation ?

[sacx]

S = d/t

for the first 12 mins

39 = d/12
d = 39 * 12/60 (12/60 to convert mins to hours)
d - 7.8 miles

So pat covered 7.8 miles in first 12 mins.

Remaining distance = 20 -7.8 = 12.2

again s = d/t

8 = 12.2/t
t = 12.2/8
t = 1 hr 32 mins or 92 mins

so total time taken = 12 +92 = 104 ( approx)

B

Is there something I am missing? the OA is C

[scoobydooby]

am getting 104 as well

whats the source quocbao?

[Ossa]

Unless she took a break, I also think the answer is B.

On a 20 mile course, Pat bicycled at an avg rate of 39 miles / h for the first 12 min and , without a break, ran the rest of the distance at an avg rat of 8 miles / h. How many minutes did Pat take to cover the entire course ?

A. 75
B. 105
C. 117
D. 150
E. 162

OA is C

Is there an easy way to solve this problem without a lot of calculation ?

[hrishikesh05]

The answer is not B

The answer is C

The questions ask how much time did it take to cover the entire distance which is the 12 + 105 = 117 mins

You guys are forgetting to add the 12 mins covered at 39 mph

[NethraN]

I too got 104 ...

@hrishikesh05: as you see the explanation above 104 is after adding the 12 mins....could you please explain how you arrived at 117???

[psmarathe]

12 mins are already tacken in to consideration.

[Mustang]

The answer is not B

The answer is C

The questions ask how much time did it take to cover the entire distance which is the 12 + 105 = 117 mins

You guys are forgetting to add the 12 mins covered at 39 mph

Wht?!!!!

[krisraam]

IMO B

Thanks
Raama

[vittalgmat]

I think OA has the problem. Pls check it again!!.
I get B as well.

[quocbao]

Sorry for late replying. OA is B. This was my mistake when I post the question.

What I want to ask in this question is that whether there is a way to finish the question easier ? Like plugging the number back to the question ? Will it be faster ?