A gives B a start of 10 metres in a 100 metre race and still beats him by 1.25 seconds. How long does B take to complete the 100 metre race if A runs at the rate of 10 m/sec?	Select the correct option
A) 8 seconds	B) 10 seconds	C) 16.67 seconds	D) 12.5 seconds	E) None
Solution:   A gives B a start of 10 metres in a 100 metre race. This means that when A runs 100 metres, B runs only 90 metres.   Despite that start, A beats B by 1.25 seconds.   As A is running at the speed of 10 m/sec, he will take 10 seconds to complete the 100 metre race. And B takes  10 + 1.25= 
<gadget id="calculator"> 10 + 1.25</gadget>
<output>11.25</output>
11.25 seconds to cover 90 metres.   Therefore, the speed at which B is running= 8 m/sec.   Running at 8 m/sec, B will take = 12.5 seconds to complete the 100 metre race.   Hence the correct answer is 12.5 seconds
<result>D</result>
A gives B a start of 10 metres in a 100 metre race and still beats him by 1.25 seconds. How long does B take to complete the 100 metre race if A runs at the rate of 10 m/sec?