70) At room temperature plain carbon steel contains

71) The LCM of 2, 3, 4 is

72) Simple interest for Rs. 2000 in two years at an interest rate of 5 % is

73) A ladder of 5 m length is kept leaning against a wall such that its tip is along the top of the wall. The lower end of t he ladder is 4 m away from the base of the wall. Then the height of the wall is

74) A train runs for 30 minutes at the speed of 50 km/hr and the next 30 minutes at the speed of 60 km/hr. Then the average speed is