Question
A man can go on a motor boat with a speed of 15 km/hour
in still water to a certain upstream point and come back to the starting point in a river which flows at a speed of 5km/hour. Find the average speed of motor boat for total journey?Solution
Let, the speed of boat be b km/hour and speed of current be s km/hour Average speed = 2xy/(x+y) (here, x is speed of downstream and y is speed of upstream)               = (2 (b+s)(b-s))/((b+s+b-s))               = (b2 - s2)/b               = (225 - 25)/15 = 200/15 = (40/3) km/hour Alternate Method :- 
Average speed = (Total distance covered)/(total time taken)               = (2×60)/9 = 120 /9 = 40/3 kmph
A horse is tethered to a peg fixed at one corner of a rectangular grass field measuring 45 metres in length and 25 metre...
What is the smallest natural number that should be added to 1030 so that the square root of the sum is a natural number?
Find the Square root of √1681
Calculate the lateral surface area of a right circular cone having a radius of 5 cm and a height of 12 cm.
Find the square of 572
Solve the following :-
If the average of two numbers is 13 and the square root of their product is 12, then the difference between the numbers is:
Find the square root of 0.0324.
Two times a number, added to the square of that number, gives 3. What could be the possible answer for this number?
What is the square root of 5476?
