11.

Two trains of lengths 150 m and 250 m pass each other with constant speeds on parallel tracks in opposite directions. The drivers and guards are at the extremities of the trains. The time gap between the drivers passing each other and first driver-guard pair passing each other is 30 s. How much later will the other driver-guard pair pass by?

• 10 s

• 20 s

• 30 s

• 50 s

In a room, we have one grandfather, two fathers, two sons and a grandson. the age of one father is seven times the age of his son. The age of the other father is twice his son's age. Assuming that there are only3 people in the room and the grandfather is 70 years old, how old is the grandson?

• 1

• 2

• 5

• Cannot be determined

A hemispherical bowl is being filled with water at a constant volumetric rate. the level of water in the bowl increases

• in direct contact to time

• in inverse proportion to time

• faster than direct proportion to time

• slower than direct proportion to time

Equal masses of two liquids of densities 6 kg/m³ and 4 kg/m³ are mixed thoroughly. The density of the mixture is

• 4.8 kg/ m³

• 5.0 kg/ m³

• 5.2 kg/ m³

• 5.4 kg/ m³

Two points A and B on the surface of the Earth have the following latitude and longitude coordinates.

A : 30° N, 45° E

B : 30° N, 135° W

If R is the radius of the Earth, the length of the shortest path from A to B is

• $\frac{\mathrm{\pi R}}{6}$

• $\frac{2\mathrm{\pi R}}{3}$

Amoebae are known to double in 3 min. Two identical vessels A and B, respectively contain one and two amoebas to start with. The vessel B gets filled in 3 hours. When will A get filled?

• 3 hours

• 2 hours 57 min

• 3 hours 3 min

• 6 hours

Students of a school are divided into 4 groups. What is the probability that three friends get into the same group?

• $\frac{3}{4}$

• $\frac{1}{64}$

• $\frac{1}{16}$

• $\frac{1}{3}$

A fruit vendor buys 120 Shimla apples at 4 for Rs. 100, and 120 Golden apples at 6 for Rs. 100. She decides to mix them and sell at 10 for RS. 200. She will make

• no profit, no loss

• a loss of 4%

• a gain of 4%

• a loss of 10%

4⁰ + 4² + 4^-2 + 4^1/2 + 4^-1/2 =

• 4⁰

• $4^{2\frac{1}{2}} + 4^{-2\frac{1}{2}}$

• $19\frac{9}{16}$

• $22\frac{9}{16}$

In an enclosure there were both crows and cows. If there were 30 heads and 100 legs, what fraction of them are crows?

• 1/3

• 1/ 4

• 1/ 10

• 3/ 10