a2zinterviews

41.	Of the three numbers, the sum of the first two is 45; the sum of the second and the third is 55 and the sum of the third and thrice the first is 90. The third number is
	A.  10
	B.  20
	C.  30
	D.  40

Solution

Let the number be x, y and Z. = Then, x+y=45, y+z=55&3x+z=90 ‹=›y=45-x, z=55-y = 55-(45-x) = 10+x ‹=›Therefore 3x+10+x = 90 or x = 20. y=(45-20)=25 and z=(10+20)= 30. Therefore Third number = 30.

42.	Two different natural numbers are such that their product is less than their sum. One of the numbers must be
	A.  1
	B.  2
	C.  3
	D.  4

Solution

Since 1. x<1+x, so one of the numbers is 1.

43.	In a two digit number, the digit in the units place is four times the digit in ten's place and sum of the digits is equal to 10. What is the number?
	A.  25
	B.  28
	C.  32
	D.  36

Solution

Let the ten digits be x. Then,units digit=4x Therefore x + 4x = 10 ‹=›5x = 10 ‹=›x= 2. So, ten's digit = 2, unit's digit = 8. Hence, the required number is 28.

44.	The sum of the digits of a two digit number is 9 less than the number. Which of the following digits is at units place of the number?
	A.  1
	B.  2
	C.  3
	D.  Data inadequate

Solution

Let the ten's digit be x and unit's digit be y. Then, (10 x + y)-(x + y)=9 or x=1. From this data, we cannot find y, the units digit. So, the data is inadequate.

45.	What is the sum of two consecutive even numbers, the difference of whose squares is 84?
	A.  34
	B.  38
	C.  42
	D.  46

Solution

Let the numbers be x and x + 2. Then, (x + 2)2–x2 = 84 ‹=›4x + 4 = 84 ‹=›4x = 80 ‹=›x = 20. Required sum = x+(x+2)= 2x+2 = 42.