the average age of a group of persons going for picnic is 16 years . 12 new persons with an average age of 15 years join the group on the spot due to which their average age becomes 15.5 years . the number of persons initially going for picnic is
solution let the initial number of persons be x . then 16 x + 12 x 15 = 15.5 ( x + 20 ) = 0.5 x = 6 x = 12 . answer c
divide(subtract(multiply(15.5, 12), multiply(12, 15)), subtract(16, 15.5))