Quantitative Aptitude - Numbers and Algebra
21. If x+y+z=0,then x2/yx + y2/zx + z2/xy equal
- Option : D
- Explanation : x2/yx + y2/zx + z2/xy
...(since, x+y+z=0 x3+y3+z3=3xyz)
(x3+y3+z3) / xyz = 3xyz / xyz = 3.
- Option : B
- Explanation : Increase after 5 years should have been 7 x 5 = 35 years. But since average remains same, diference in their age is 35 years.
- Option : D
- Explanation : L.C.M. of 9, 10 and 15 = 90 ∴ 1936 = 90 x 21 + 46 (Remainder). But a part of this remainder is 7. 39 should be subtracted from 1936.
24. What is the maximum sum of the series 60, 58, 56, 54, 52, ?
- Option : C
- Explanation :
Since d = -2, maximum sum of the series will be sum of all the positive terms.
Least positive term of the series is 2 or 0 (both giving equal sum)
Let, 2 be the nth term
2 = 60 + (n 1) - 2
=> n = 30
Required sum = 30/2 (60 + 2) = 930
