Aptitude :: PercentagePage 2
9.  28% of 450 + 45% of 280 = x.  (a)152  (b)252  (c)250  (d)260 

Answer is: Bx = [28/100 X 450 + 45/100 X 280]
x = 126 + 126 = 252
10.  9% of ? = 63  (a)600  (b)700  (c)750  (d)800 

Answer is: BLet 9% of x = 63
9/100 X x = 63
x = 63 X 100/9 = 700
11.  If sales tax be reduced from 7/2% to 10/3%, then what difference does it make to a person who purchases an article wit marked price of Rs. 8400?  (a)14  (b)16  (c)18  (d)20 

Answer is: ARequired difference = [7/2% of Rs. 8400]  [10/3% of Rs. 8400)]
Required difference = (7/2  10/3)% of Rs. 8400.
Required difference = 1/6% of 8400.
Required difference = 1/6 X 1/100 X 8400.
Required difference = 14.
12.  An inspector rejects 0.08% of the meters as defective. How many will be examine to reject 2?  (a)2400  (b)2500  (c)2600  (d)2700 

Answer is: BLet the number of meters to be examined be x.
Then, 0.08% of x = 2
So, [8/100 X 1/100 X x] = 2
x = (2 X 100 X 100)/8 = 2500.
13.  Sixty five of a number is 21 less than four fifth of that number. What is the number ?  (a)130  (b)140  (c)150  (d)160 

Answer is: BLet the number be x.
Then, (4/5)x  (65% of x) = 21
(4/5)x  (65/100)x = 21
15x = 2100
x = 140.
14.  In expressing a length 81.472 km as nearly as possible with three significant digits, Find the percentage error?  (a)0.012%  (b)0.025%  (c)0.034%  (d)0.039% 

Answer is: CLet Error = (81.5  81.472) km = 0.028
∴ Required percentage = 0.028/81.472 X 100% = 0.034%
15.  In an election between two candidates, 75% of the voters cast their votes, out of which 2% of the votes were declared invalid. A candidates got 9261 votes which were 75% of the total valid votes. Find the total number of votes enrolled in that election.?  (a)14800  (b)15800  (c)16800  (d)16500 

Answer is: CLets the total number of votes enrolled be x.
Then, Number of votes cast = 75% of x.
Valid votes = 98% of (75% of x).
∴ 75% of [98% of (75% of x)] = 9261
(75/100) X (98/100) X (75/100) X x = 9261
x = (9261 X 100 X 100 X 100 X 75)/(75 X 98) = 16800
x = 16800.
16.  Mr. Jones gave 40% of the money he had, to his wife. He also gave 20% of the remaining amount to each of his three sons. Half of the amount now left was spent on miscellaneous items and the remaining amount of Rs. 12000 was deposited in the bank. How much money did Mr. Jones have initially?  (a)100000  (b)10000  (c)1000  (d)100 

Answer is: ALet the initial amount with Mr. Jones be x.
Then, (1/2)[100  (3 X 20)]% of (100  40)% of x =12000.
(1/2) X (40/100) X (60/100) X x = 12000.
(3/25)x = 12000.
x = Rs.100000.
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