A car owner buys petrol at Rs 7.50, Rs. 8 and Rs. 8.50 per litre for three successive years. What approximately is the average cost per litre of petrol if he spends Rs. 4000 each year ?

The standard deviation of the set {10, 10, 10, 10, 10} is

If the average of 31, x, 42, 39, 56, 78, 83 and 91 is 58.5, then what is the value of x?

The mode and median of the data 8, 6, 8, 7, 8, 6, 8, 7, 6 is

The mean of the data 1, 2, 10, 18, 3, 17, 19 is

If the average age of 20 students in Class-I is 10 years and average age of 25 students in Class II is 12 years, find the average age (in years) of all students.

20 pens and 46 pencils were purchased for Rs. 235. If the average price of a pencil is Rs. 2.50 then calculate the average price (in Rs.) of a pen.

The average of two numbers is 10 and the product of two numbers is 96. Find the two numbers.

Average of the runs of 133 players of a team is 38. If the average of the runs of the male players is 43 and the average of the runs of the female players is 24, then what will be the ratio of the total runs of male players and the total runs of female players respectively?