a boy rides his bicycle 10 km at an average speed of 12 km / hr and again travels 12 km at an average speed of 10 km / hr. his average speed for the entire trip is approximately? Options
A) 10.7 km / hr  B) 10.8 km / hr  C) 17.8 km / hr  D) 10.5 km / hr  E) 30.8 km / hr
<gadget id="calculator">12 + 10</gadget>
<output>22</output>

<gadget id="calculator">22 / 2</gadget>
<output>11</output>

<result>B</result>
a boy rides his bicycle 10 km at an average speed of 12 km / hr and again travels 12 km at an average speed of 10 km / hr. his average speed for the entire trip is approximately?
divide(add(12, 10), const_2)
total distance traveled = 10 + 12 = 22 km / hr . total time taken = 10 / 12 + 12 / 10 = 61 / 30 hrs . average speed = 22 * 30 / 61 = 10.8 km / hr . answer : b