66) The average cost of 40 articles of a class is Rs. 30. When more articles are included the average cost is increased by 0.4. The average cost of 10 new articles is?

67) Find the distance covered by puneet in 15 hours if average speed of puneet is 1.5 times average speed of pawan who covers 336 km in 7 hours.

68) The average of 8 numbers is 280. The average of 6 of these numbers is 320. What is the average of the remaining two numbers.

69) A shopkeeper has Rs. 10 in form of 2 paise, 5 paisa and 25 paisa coins are in the ratio 25:5:2. find the number of 2 paisa coins with the shopkeeper?

70) In a mixture of 30 liters, the ratio of juice and sugar syrup is 7:3. How much more sugar syrup must be added to make its ratio 1:2?