a2zinterviews

6.	Distance between two stations A and B is 778 km. A train covers the journey from A to B at 84 km per hour and returns back to A with a uniform speed of 56km per hour. Find the average speed of the train during the whole journey?
	A.  67.0 km /hr
	B.  67.2 km /hr
	C.  69.0 km /hr
	D.  69.2 km /hr

Solution

Required average speed =(2xy / x+y)km/hr = 2 x 84 x 56 /(84 + 56) = (2 x 84 x 85 /140) = 67.2 km/hr.

7.	The avearage age of boys in a class is 16 years and that of the girls is 15 years. The average age for the whole class is
	A.  15 years
	B.  15.5 years
	C.  16 years
	D.  Cannot be computed

Solution

Clearly, to find the average,we ought to know the numbers of boys , girls or students in the class, neither of which has been given. so the data provided is inadequate.

8.	The avearge age of 36 students in a group is 14 years. when teacher’s age is included to it, the average increases by one. What is the teacher’s age in years?
	A.  31
	B.  36
	C.  51
	D.  55

Solution

Age of the teacher =(37x15 - 36x14) years = 51 years.

9.	The average of five numbers id 27. If one number is excluded, the average becomes 25. The excluded number is
	A.  25
	B.  27
	C.  30
	D.  35

Solution

Excluded number = (27 x 5 ) - ( 25 x 4) = 135 - 100 = 35.

10.	The batting average for 40 innings of a cricket player is 50 runs. His highest score exceeds his lowest score by 172 runs. If these two innings are excluded, the average of the remaining 38 innings is 48 runs. The highest score of the player is
	A.  165 runs
	B.  170 runs
	C.  172 runs
	D.  174 runs

Solution

Let the highest score be x. Then, lowest score =(x-172) = [(50 x 40)-(x+(x-172)] = 38 x 48 2x= 2000+172-1824 2x=348 x= 174.