Directions(1-5): What should come in place of question mark (?) in the following series:
1. 7415, 2271, 2171, 2107, 2071, ?
A. 2057
B. 2056
C. 2055
D. 2054
E. None of these
Sol. 7415 - 12² = 2271
2271 - 10² = 2171
2171 - 8² = 2107
2107 - 6² = 2071
2071 - 4² = 2055.
2. 500, 465, 435, 410, 390, ?
A. 365
B. 375
C. 385
D. 395
E. None of these
Sol. 500 - 35 = 465
465 - 30 = 435
435 - 25 = 410
410 - 20 = 390
390 - 15 = 375.
3. 4, 8, 12, 24, 36, ?
A. 75
B. 76
C. 72
D. 70
E. None of these
Sol. 4×2 = 8
8×1.5 = 12
12×2 = 24
24×1.5 = 36
36×2 = 72.
4. 20, 114, 565, 2256, 6765, ?
A. 13528
B. 12528
C. 13875
D. 12875
E. None of these
Sol. 20×6 - 6 = 114
114×5 - 5 = 565
565×4 - 4 = 2256
2256×3 - 3 = 6765
6765×2 - 2 = 13528.
5. 112, 146, 95, 163, 78, ?
A. 190
B. 185
C. 180
D. 175
E. None of these
Sol. 112 + 34 = 146
146 - 51 = 95
95 + 68 = 163
163 - 85 = 78
78 + 102= 180.
6. The ratio of water and milk in three vessels are 5 : 7, 7 : 9 and 8 : 5, respectively. If the mixture of the three vessels is mixed, then what will be the ratio of water and milk ?
A. 791 : 887
B. 857 : 719
C. 917 : 955
D. 875 : 976
E. None of these
Sol. Quantity of water in the mixture = 5/12 + 7/16 + 8/13 = 917/624
Quantity of milk in the mixture = 7/12 + 9/16 + 5/13 = 955/624
The required ratio is 917 : 955
7. A box contains 5 red balls, 4 blue balls, 3 yellow balls and 2 green balls. If four balls are picked at random, what is the probability that two are red, one is blue and one is green ?
A. 22/1001
B. 85/1001
C. 55/1001
D. 80/1001
E. 65/1001
Sol. Total balls = 14
Probability = (5c2 × 4c1 × 2c1 )/ 14c4 = 80/1001.
8. A basket contains 6 red balls and 10 green balls. Two balls are drawn at random one after one with replacement. What is the probability that first one is green and second one is red ?
A. 16/64
B. 18/64
C. 15/64
D. 14/64
E. None of these
Sol. Probability Required = (10/16)×(6/16).
9. Out of a total profit of Rs 14,000, Anish received Rs 10000 as his share. If Anish invested Rs 20000 for 6 months while Balu invested his amount for the whole year, then find the amount that Balu invested ?
A. Rs 5,000
B. Rs 3,000
C. Rs 5,500
D. Rs 4,000
E. None of these
Sol. Profit ratio = 10000 : 4000 = 5 : 2
So
20,000×6 : 12x = 5 : 2
10000/x = 5/2
x = 4,000.
10. It takes six times as long to row a distance against the stream as to row the same distance in favor of the stream. What is the ratio of the speed of the boat in still water to that of stream ?
A. 6 : 7
B. 5 : 8
C. 8 : 5
D. 7 : 5
E. 5 : 7
Sol. A = [(tu + td) / (tu – td)] × B
So
A = [(6x + x) / (6x- x)] × B
So, A/B = 7/5.
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