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Tuesday, March 5, 2013

Civil Service Commission Professional or Sub-Professional Reviewer - Page 85/159

Mathematics Test III Solution - Page 85

18. What part of an hour elapses between 9:52 AM and 10:16 AM ?

= 10:16 - 9:52

10:16 is also equal to 9:76 since 76 is equal to 1 hour and 16 minutes. 9 hours + 1 hour and 16 minutes = 10:16.

= 9:76 - 9:52 = 24 minutes

= 24 minutes x    1 hr   
                       60 min

=  24 / 60 hrs.

= 2 / 5 hours *Ans.

19. If the ratio of boys to girls is 3 : 7 . If the class has 40 students, how many additional boys are needed to enroll to make the ratio 2 : 1 ?

3x + 7x = 40      The number of boys : 3x = 3(4) = 12

      10x = 40      The number of girls  : 7x = 7(4) = 28

          x =  40     since the desired ratio of boys to girls
                 10     is 2 : 1 .

          x = 4        the required number of boys is 2 x 28 = 56
                          so 56 - 12 = 44 more boys are needed. *Ans.

20. If 45 feet of uniform wire weigh 5 kilograms, what is the weight of 30 yards o the same wire ?

Let x - be the length of 30 yards of the same wire.

30 yards x  3 feet  = 90 feet
                  yard

 x  =  5 
90    45

 x  =  1 
90     9

x = 10 kgs. *Ans.

21. A school has enough oatmeal to feed 15 children in 4 days. If 5 more children are added, how many days will the oatmeal last ?

This problem is an example of an inverse proportion.

4 : 1/5 = x : 1 / (15 + 5)

4 : 1/15 = x : 1/20

 1 x = 4 ( 1 )
15          20

 x  =  1 
15    5

x =  1  (15)
       5

x = 3 days *Ans.

Civil Service Reviewer Post 85/159