Exams

Assume both trains meet after 'p' hours after 7 a.m.
Distance covered by train starting from A in 'p' hours = 20p km
Distance covered by train starting from B in (p-1) hours = 25(p-1)
Total distance = 200
=> 20x + 25(x-1) = 200
=> 45x = 225
=> p= 5
Means, they meet after 5 hours after 7 am, ie, they meet at 12 p.m.

The logic behind the sequence given in the question is +4, +4, +6, +6
Therefore, the sequence which follows the same logic in the given options is DHLRX.

Let the 6 digits of the required 6 digit number be abcdef

Then, the number to be odd number the last digit must be odd digit i.e 3, 5, 7 or 9

The first digit cannot be ‘0’ => possible digits = 3, 5, 7, 2, 6, 8

Remaining 4 places can be of 6 x 5 x 4 x 3 ways

This can be easily understood by

Therefore, required number of ways = 6 x 6 x 5 x 4 x 3 x 4 = 36 x 20 x 12 = 720 x 12

= 8640 ways.

The earth's atmosphere is composed of 4 layers. 

1. Troposphere

2. Stratosphere

3. Ionosphere

4. Mesosphere

The ozone layer is located in the lower region of the Stratosphere which extends at 11 - 50 kms from the Earth's suface.

Spalling hammer is used for Rough dressing of stones.