the mean daily profit made by a shopkeeper in a month of 30 days was rs . 350 . if the mean profit for the first fifteen days was rs . 245 , then the mean profit for the last 15 days would be
"average would be : 350 = ( 245 + x ) / 2 on solving , x = 455 . answer : d"
divide(subtract(multiply(30, 350), multiply(15, 245)), 15)