২৬০৭১
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?
উত্তর
3391
২৬০৭২
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.
উত্তর
60.0km/hr
২৬০৭৩
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
উত্তর
24 km
২৬০৭৪
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?
উত্তর
84 km / hr
২৬০৭৫
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?
উত্তর
20°
২৬০৭৬
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?
উত্তর
12
২৬০৭৭
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:
উত্তর
7
২৬০৭৮
A short distance athlete has taken 60 sec to cover 100m. If he makes 30 steps in 9, sec how many steps has he taken in that time?
উত্তর
None
২৬০৭৯
A manufacturer sells three products i.e A, B C. Product A costs 200 and sells for 250, product 150 and sells for 180, Product C cost 100 and sells for 110. On which product, he has maximum percentage of profit?
উত্তর
A only
২৬০৮০
a man can row at 5 km/hr in still water. If the velocity of the current is 1 km/hr and it takes him 1 hour to row to a place and come back, how far is the place?
উত্তর
5 km