Question
The present ages of Priya’s father and mother are in
the ratio R:S. If the father’s age increases by 4 years and the mother’s age decreases by 4 years, the ratio becomes 13/7. If the sum of their actual ages is 80 years, find the father’s current age.Solution
ATQ, Father’s age = x Mother’s age = y x + y = 80 — (1) (x + 4) / (y − 4) = 13 / 7 7(x + 4) = 13(y − 4) 7x + 28 = 13y − 52 7x − 13y = −80 — (2) Multiply (1) by 13: 13x + 13y = 1040 Add with (2): (13x + 13y) + (7x − 13y) = 1040 − 80 20x = 960 x = 960 / 20 = 48 Required answer = 48 years
38    40    83    254    ?     5126
Find the wrong number in the given series.
3 1.5 1.5 ? 4.5 11.25
...If 7             16      x    90       171          292
Then, 2x 2 +  1 + x ...
98    219    75    244    ?    273
Find the maximum number of trees which can be planted, 25 meters apart, on the two sides of a straight road 2125 meters long
43 36 50 29 ? 22
...6Â Â Â Â Â Â Â Â Â Â 5Â Â Â Â Â Â Â Â Â Â 40Â Â Â Â Â Â Â Â Â Â Â 32Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â 249Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â 240
104   106   110   113   ?   126
6 2 8 ? 84 416
...75    196    52    221    ?    250