Abhishek starts to paint a fence on one day. On the second day, two more friends of Abhishek join him. On the third day 3 more friends of him join him and so on. If the fence is completely painted this way in exactly 20 days, then find the number of days in which 10 girls painting together can paint the fence completely, given that every girl can paint twice as fast as Abhishek and his friends(Boys)? (Assume that the friends of Abhishek are all boys).
Answers
A) 20	B) 40	C) 45	D) 77	E) 87
Number of men working on first day = 1   Number of men working on second day = 3   Number of men working on second day = 6 and so on..   Total number of boys till the end of the work = [n(n + 1) (n + 2)] / 6   = [20 x 21 x 22] / 6 = 1540   Given that every girl paints twice as fast as Abhishek’s friends.   Hence, 20 girls work is being done.   Thus, the number of days taken to paint the fence = 1540/20= 
<gadget id="calculator">1540/20</gadget>
<output>77</output>
77.   ANSWER:77
<result>D</result>
Abhishek starts to paint a fence on one day. On the second day, two more friends of Abhishek join him. On the third day 3 more friends of him join him and so on. If the fence is completely painted this way in exactly 20 days, then find the number of days in which 10 girls painting together can paint the fence completely, given that every girl can paint twice as fast as Abhishek and his friends(Boys)? (Assume that the friends of Abhishek are all boys).