A square is inscribed in a circle of diameter 2a and another square is circumscribing circle. The difference between the areas of outer and inner squares is:
12 marbles are selected at random form a large collection of white , red, green and yellow marbles . The number of marbles of each color is unlimited. Find the probability that the selection contains at least one marble of each color ?
a motor -cycle covers 40 Km with a speed of 20 km /hr. Find the speed of the motor -cycle for the next 40 km journey so that the average speed of the whole journey will be 30 km / hr.
A man can row 6 km / hr in still water. It the speed of the current is 2 km / hr , it takes 3 hrs more in upstream than in the downstream for the same distance . The distance is
The respective ratio between the speed of a car , a train , and a bus is 5 : 9 : 4 . The average speed of the car, bus and train is 72 km / hr together . what is the average speed of the car and the train together?
Three angles of a triangle are in proportion 5: 6: 7. Then what is the difference in degrees between he biggest and the smallest angles?
A water tank has two taps ( Tap-1 and Tap-2) : Tap-1 can fill a tank in 8 hours and Tap-2 can empty the tank in 16 hours . How long will they take to fill the tank if both taps are opened simultaneously but Tap -2 is closed after 8 hours?
The average of the three numbers x , y and z is 45 , x is greater than the average of y and z by 9. The average of y and z is greater than y by 2 .Then the difference of x and z is:
A can finish a work in 5 days and B takes 4 days to do the same work . If the work is increased by 8 times, how many days will it take for both of them to finish the work if they work together?
Alam sold two vehicles for Tk. 46000 each . If he gained 10% on the first and lost 10% on another , then what is his percentage profit or loss in this transaction?