A certain list consists of 21 different numbers. If n is in the list and n is 7 times the average (arithmetic mean) of the other 20 numbers in the list, then n is what fraction of the sum of the 21 numbers in the list?  Choose one
A) 7/27  B) 1/6  C) 1/5  D) 4/21  E) 5/21
series : a1, a2....a20,n   sum of a1+a2+...+a20 = 20*x (x = average)   so, n = 7*x   Hence, a1+a2+..+a20+n = 27x   So, the fraction asked = 7x/27x = 7/27   7/27nswer 7/27
<result>A</result>
A certain list consists of 21 different numbers. If n is in the list and n is 7 times the average (arithmetic mean) of the other 20 numbers in the list, then n is what fraction of the sum of the 21 numbers in the list?