Monday, 20 April 2015

EXERCISE 6.A (OBJECTIVE TYPE QUESTIONS) (IN 40 45 SOLUTION)

                  41.  The average price of three items of furniture is Rs. 15000. If their prices are in the ratio 3 :   5 : 7, the price of the cheapest item is:

a)      Rs. 9000
b)      Rs. 15000
c)       Rs. 18000
d)      Rs.21000
42.       Of the four numbers, the fist is twice the second, the second is one-third of the third and the third is 5 times the fourth. The average of the numbers is 24.75. The largest of these numbers is:
a)      9
b)      25
c)       30
d)      None of these
43.       Of the four numbers, whose average is 60, the first is one-fourth of the sum of the last three. The first number is:
a)      15
b)      45
c)       48
d)      60.25
44.       Of the three numbers, the first is twice the second and the second is twice the third. The average of the reciprocal of the numbers is 7/72. The numbers are:
a)      16,8,4
b)      20,10,5
c)       24,12,6
d)      36,18,9
45.       Of the three numbers, the average of the first and the second is greater than the average of the second and the third by 15. What is the difference between the first and the third of the three numbers?
a)      15
b)      45
c)       60
d)      Data inadequate
e)      None of these
    ANSWERS

       41.A
       42.D
       43.C
      44.C
     45.E
SOLUTION
 41.       Let their prices be 3x, 5x and 7x.
Then, 3x + 5x and 7x.
Cost of cheapest item = 3x = Rs. 9000.
42.       Let the fourth number be x.
Then, third number = 5x, second number = 5x / 3 and first number = 10 x / 3
X + 5x/ 3 + 10x / 3 = (24.45, 15 and 30.
Largest number = 45.
43.       Let the first number be x.
Then, sum of the four numbers = X + 4x = 5x.
So, 5x / 4 = 60 or x = (60 x 4 / 5) = 48.
44.       Let the third number be x. then, second number = 2x. first number = 4x.
1/x + 1/2x + 1/4x = (7/72 x 3) or 7/4x = 7 /24 or 4x = 24 or x = 6.
So, the numbers are 24, 12 and 6.
45.       Let the numbers be X, y and z.
Then, (x + y/2) +(Y + z/2) = 15 or (x + y) – (x + z) = 30 or x = z = 30.

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