P beats Q by 5 seconds in a race of 1000 m and Q beats R by 5 metres in a race of 100 m. By how many seconds does P beats R in a race of 1000 m?	Choose the correct answer.
A) 5 sec B) 7 sec C) 10 sec D) Can't be determined E) None of these
Explanation :   If P takes t seconds to run 1000 m, then Q takes (t+5) sec.   In (t+5) sec Q runs 100 m whereas R runs only 950 m.   R runs 1000 m in (1000/950)x(t+5)sec.   P takes t seconds to cover 1000m , while R takes (20t/19+100/95)sec.   From the data given, we cannot determine t .   Answer : Can't be determined
<result>D</result>
P beats Q by 5 seconds in a race of 1000 m and Q beats R by 5 metres in a race of 100 m. By how many seconds does P beats R in a race of 1000 m?