The average age of 40 students of a class is 16 years. If the average age of 24 students is 15.5 years and that of the 15 students is 16 2⁄3 years, then the age of 40th student is
A man starts walking at 6.30 a.m. and wants to cover a distance of 30km. His initial speed is 6 kmph and after covering three-fifth distance, he reduces his speed by 2 kmph. At what time will he complete his walk?
The average of 21 numbers is 12. The average of the first 11 numbers is 9 and the average of the last 11 numbers is 15. What is the value of the middle number?