The average of first three numbers is thrice the fourth number. If the average of all the four numbers is 5, then find the fourth number.
Options:
A . 2
B . 4
C . 4.5
D . 5
Answer: Option A Answer: (a)Let the numbers be a, b, c, ${\text"a + b + c"}/3$ = 3d ⇒ a + b + c = 9d Again, ${\text"a + b + c + d"}/4$ = 5 ⇒ a + b + c + d = 20 ⇒ 9d + d = 20 ⇒ 10d = 20 ⇒ d = 2
Submit Comment/FeedBack