[B].
[C].
[D].
Answer: Option A
Explanation:
Let Sn = (1 + 2 + 3 + … + 45)
This is an A.P. in which a = 1, d = 1, n = 45 and l = 45
| Sn = | n | (a + l) | = | 45 | x (1 + 45) = (45 x 23) = 1035 |
| 2 | 2 |
Required sum = 1035.
[B].
[C].
[D].
Answer: Option C
Explanation:
| Speed = | 45 x | 5 | m/sec | = | 25 | m/sec. | ||
| 18 | 2 |
Time = 30 sec.
Let the length of bridge be x metres.
| Then, | 130 + x | = | 25 |
| 30 | 2 |
2(130 + x) = 750
x = 245 m.
Video Explanation: https://youtu.be/M_d8WufJWKc
A. 2 : 1
B. 3 : 1
C. 3 : 2
D. 4 : 3
[B].
[C].
[D].
Answer: Option B
Explanation:
| (10)150 ÷ (10)146 = | 10150 |
| 10146 |
= 10150 – 146
= 104
= 10000.
[B].
[C].
[D].
Answer: Option A
Explanation:
Required number = H.C.F. of (91 – 43), (183 – 91) and (183 – 43)
= H.C.F. of 48, 92 and 140 = 4.
[B].
[C].
[D].
Answer: Option B
Explanation:
639 is not divisible by 7
2079 is divisible by each of 3, 7, 9, 11.
[B].
[C].
[D].
Answer: Option C
Explanation:
Let the speed of each train be x m/sec.
Then, relative speed of the two trains = 2x m/sec.
| So, 2x = | (120 + 120) |
| 12 |
2x = 20
x = 10.
| Speed of each train = 10 m/sec = | 10 x | 18 | km/hr = 36 km/hr. | ||
| 5 |