SUPER SHOT IN 30 MIN

Who Will spend more electrical energy ? 500 W TV set in 30 mins, or 600 W heater in 20 mins ?

Two taps can fill an empty cistern in 8 min and 20 min, respectively. However, together . They take 30 min to fill it because of a leak. How much time will the leak take to empty a full cistern?

It takes 15 min to completely fill an oil tank. However the oil tank is being used via an outlet in the tank which can empty it in 30 min. If this outlet is open, how much time will it take to fill the tank completely? (A) 20 min (B) 25 min (C ) 30 min (D) 40 min

Vishal covers a distance of 20 km in 30 min. If he covers half of the distance in 18 min, what should be his speed to cover the remaining distance and completes the whole journey in 30 min.