Average expenditure of a person for the first 3 days of a week is Rs. 320 and for the next 4 days is Rs. 420. Average expenditure of the man for the whole week is:  Pick one
A) 350  B) 370  C) 390  D) 360  E) none

Rationale: explanation : assumed mean = rs . 320 total excess than assumed mean = 4 × ( rs . 420 - rs . 350 ) = rs . 280 therefore , increase in average expenditure = rs . 280 / 7 = rs . 40 therefore , average expenditure for 7 days = rs . 320 + rs . 40 = rs . 360 correct option : d
Answer: D