[B].
[C].
[D].
Answer: Option B
Explanation:
Sum of the present ages of husband, wife and child = (27 x 3 + 3 x 3) years = 90 years.
Sum of the present ages of wife and child = (20 x 2 + 5 x 2) years = 50 years.
Husband’s present age = (90 – 50) years = 40 years.
[B].
[C].
[D].
Answer: Option B
Explanation:
| 2056 x 987 | = 2056 x (1000 – 13) |
| = 2056 x 1000 – 2056 x 13 | |
| = 2056000 – 26728 | |
| = 2029272. |
[B].
[C].
[D].
Answer: Option B
Explanation:
| Given Exp. | = (397)2 + (104)2 + 2 x 397 x 104 |
| = (397 + 104)2 | |
| = (501)2 = (500 + 1)2 | |
| = (5002) + (1)2 + (2 x 500 x 1) | |
| = 250000 + 1 + 1000 | |
| = 251001 |
[B].
[C].
[D].
Answer: Option C
Explanation:
| Speed = | 78 x | 5 | m/sec | = | 65 | m/sec. | ||||
| 18 | 3 |
Time = 1 minute = 60 seconds.
Let the length of the tunnel be x metres.
| Then, | 800 + x | = | 65 | ||
| 60 | 3 |
3(800 + x) = 3900
x = 500.
[B].
[C].
[D].
Answer: Option D
Explanation:
By hit and trial, we put x = 5 and y = 1 so that (3x + 7y) = (3 x 5 + 7 x 1) = 22, which is divisible by 11.
(4x + 6y) = ( 4 x 5 + 6 x 1) = 26, which is not divisible by 11;
(x + y + 4 ) = (5 + 1 + 4) = 10, which is not divisible by 11;
(9x + 4y) = (9 x 5 + 4 x 1) = 49, which is not divisible by 11;
(4x – 9y) = (4 x 5 – 9 x 1) = 11, which is divisible by 11.
[B].
[C].
[D].
Answer: Option D
Explanation:
| We know that (12 + 22 + 32 + … + n2) = | 1 | n(n + 1)(2n + 1) |
| 6 |
| Putting n = 10, required sum = | 1 | x 10 x 11 x 21 | = 385 | ||
| 6 |