Directions (Q. 1-5): What value should come in place of question mark (?) in the following number series?
1. 124 215 342 511 ? 999
1) 695
2) 625
3) 728
4) 806
5) 573
2. 516 256 126 61 28.5 ?
1) 12.25
2) 16.75
3) 14.25
4) 20.20
5) 18.7
3. 7 21 50 109 ? 467
1) 198
2) 228
3) 372
4) 402
5) 275
4. 18 82 118 134 138 ?
1) 132
2) 198
3) 125
4) 138
5) 92
5. 5 22 103 406 ? 2422
1) 1516
2) 1298
3) 1136
4) 1602
5) 1213
6. A mixture of milk and water contains 7% water. What quantity of pure milk should be added to 12 litres of mixture to reduce water to 4%?
1) 5 litres
2) 6 litres
3) 7 litres
4) 8 litres
5) 9 litres
7. Two candles of the same height are lighted at the same time. The first is consumed in 6 hours and the second in 4 hours. Assuming that each candle burns at a constant rate, in how many hours after being lighted, was the first candle was twice the height of the second?
1) 3.5 hrs
2) 2 hrs
3) 4 hrs
4) 3 hrs
5) 2.5 hrs
8. Three friends Anil, Ravi and Sumit jog around a circular park and complete round in 21, 18 and 24 minutes respectively. In how many hrs will all the three meet again at starting point?
1) 8 hrs
2) 8.4 hrs
3) 6.5 hrs
4) 7.5 hrs
5) 9 hrs
9. With the help of the digits 1, 2, 3 and 4 find the sum of all 4 – digits numbers provided that the digits are not repeated.
1) 66,660
2) 6500
3) 40375
4) 100013
5) None of these
10. A, B and C can do a piece of work in 20, 30 and 100 days respectively. If A worked alone on the first day, B worked alone on the second day, C worked alone on the third day, A worked alone on the fourth day, and so on, then in how many days the work got completed?
1) 29 days
2) 28 days
3) 31 1/2 days
4) Can't be determined
5) None of these
Answers
1. 3
The series is
5^3 – 1 = 124
6^3 – 1 = 215
7^3 – 1 = 342
8^3 – 1 = 511
9^3 – 1 = 728
10^3 – 1 = 999
Required answer = 728
2. 1
The series is
3. 2
The series is
4. 4
The series is
5. 5
The series is
6. 5; The quantity of pure milk to be added
= {12 * (7 - 4)}/4 = 9 litres
7. 4
h = height of candles
The first candle consumed in 6 hours and the second in 4 hours."
first candle shortens by h/6 each hour
second candle shortens by h/4 each hour
height of first candle after t hours = h - th/6 = h(1 - t/6)
height of second candle after t hours = h - th/4 = h(1 - t/4)
h(1 - t/6) = 2h(1 - t/4)
(1 - t/6) = 2(1 - t/4)
1 - t/6 = 2 - t/2
t/2 - t/6 = 1
6t - 2t = 12
t = 12/4 = 3 hours
8. 2
Required time = LCM of 21, 18, 24 min = 504 mins = 8.4 hrs
9. 1;
1 × 2 × 3 × 4 = 24 numbers, it mean at every place digits
will occur six times.
Sum of one column = 6 ( 1 + 2 + 3 + 4) = 60
Hence, sum of all the numbers
= 60 × (100 + 101 + 102 + 103)
= 60 × 1111 = 66660
10. 3
A's, B's and C's 1 day work = 1/20 + 1/30 + 1/100
Total 3 day's work = 28/300
Total 30 day work = 280/300
Remaining work = 20/300 = 1/15
Now A's 1 day work = 1/20
Then remaining work = (1/60)/(1/30) = 1/2
Now, B's then B complete the remaining work in 1/2
Total number of days = 31 1/2 days.
1. 124 215 342 511 ? 999
1) 695
2) 625
3) 728
4) 806
5) 573
2. 516 256 126 61 28.5 ?
1) 12.25
2) 16.75
3) 14.25
4) 20.20
5) 18.7
3. 7 21 50 109 ? 467
1) 198
2) 228
3) 372
4) 402
5) 275
4. 18 82 118 134 138 ?
1) 132
2) 198
3) 125
4) 138
5) 92
5. 5 22 103 406 ? 2422
1) 1516
2) 1298
3) 1136
4) 1602
5) 1213
6. A mixture of milk and water contains 7% water. What quantity of pure milk should be added to 12 litres of mixture to reduce water to 4%?
1) 5 litres
2) 6 litres
3) 7 litres
4) 8 litres
5) 9 litres
7. Two candles of the same height are lighted at the same time. The first is consumed in 6 hours and the second in 4 hours. Assuming that each candle burns at a constant rate, in how many hours after being lighted, was the first candle was twice the height of the second?
1) 3.5 hrs
2) 2 hrs
3) 4 hrs
4) 3 hrs
5) 2.5 hrs
8. Three friends Anil, Ravi and Sumit jog around a circular park and complete round in 21, 18 and 24 minutes respectively. In how many hrs will all the three meet again at starting point?
1) 8 hrs
2) 8.4 hrs
3) 6.5 hrs
4) 7.5 hrs
5) 9 hrs
9. With the help of the digits 1, 2, 3 and 4 find the sum of all 4 – digits numbers provided that the digits are not repeated.
1) 66,660
2) 6500
3) 40375
4) 100013
5) None of these
10. A, B and C can do a piece of work in 20, 30 and 100 days respectively. If A worked alone on the first day, B worked alone on the second day, C worked alone on the third day, A worked alone on the fourth day, and so on, then in how many days the work got completed?
1) 29 days
2) 28 days
3) 31 1/2 days
4) Can't be determined
5) None of these
Answers
1. 3
The series is
5^3 – 1 = 124
6^3 – 1 = 215
7^3 – 1 = 342
8^3 – 1 = 511
9^3 – 1 = 728
10^3 – 1 = 999
Required answer = 728
2. 1
The series is
3. 2
The series is
4. 4
The series is
5. 5
The series is
6. 5; The quantity of pure milk to be added
= {12 * (7 - 4)}/4 = 9 litres
7. 4
h = height of candles
The first candle consumed in 6 hours and the second in 4 hours."
first candle shortens by h/6 each hour
second candle shortens by h/4 each hour
height of first candle after t hours = h - th/6 = h(1 - t/6)
height of second candle after t hours = h - th/4 = h(1 - t/4)
h(1 - t/6) = 2h(1 - t/4)
(1 - t/6) = 2(1 - t/4)
1 - t/6 = 2 - t/2
t/2 - t/6 = 1
6t - 2t = 12
t = 12/4 = 3 hours
8. 2
Required time = LCM of 21, 18, 24 min = 504 mins = 8.4 hrs
9. 1;
1 × 2 × 3 × 4 = 24 numbers, it mean at every place digits
will occur six times.
Sum of one column = 6 ( 1 + 2 + 3 + 4) = 60
Hence, sum of all the numbers
= 60 × (100 + 101 + 102 + 103)
= 60 × 1111 = 66660
10. 3
A's, B's and C's 1 day work = 1/20 + 1/30 + 1/100
Total 3 day's work = 28/300
Total 30 day work = 280/300
Remaining work = 20/300 = 1/15
Now A's 1 day work = 1/20
Then remaining work = (1/60)/(1/30) = 1/2
Now, B's then B complete the remaining work in 1/2
Total number of days = 31 1/2 days.
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