21.

The graphs of lines x + 2y - 3 = 0 and 2x + 4y + 11 = 0

• intersect at each other

• coincide with each other

• are parallel to one another

• are perpendicular to each other

There are 10 persons in a party. If each one of them shakes hand with others exactly once. The total number of handshakes is

• 105

• 55

• 45

• None of these

A man and his wife appear for an interview for two posts. The probability of husband's selection is $\frac{1}{7}$ and that of wife's selection $\frac{1}{5}$. What is the probability of only one of them will be selected ? 

• $\frac{1}{7}$

• $\frac{2}{7}$

• $\frac{2}{5}$

• $\frac{1}{5}$

$\frac{5^{\mathrm{n} + 3} - 6 \times 5^{\mathrm{n} + 1}}{9 \times 5^{\mathrm{n}} - 2^2 \times 5^{\mathrm{n}}} \mathrm{is}$

• 91

• 19

• 10

• 1

$\frac{\sqrt{5}}{\sqrt{9 + 4\sqrt{5}} - \sqrt{9 - 4\sqrt{5}}} = ?$

• $\frac{1}{2}$

• $\frac{1}{3}$

• $\frac{1}{5}$

• $\frac{1}{4}$

A man buys two books at Rs 410 and sells both at same price. One gives him a profit of 15% and another a loss of 10%. The cost price of both book is

• 110, 260

• 120, 290

• 180, 230

• None of these

Which of the following statement is true ?

• ${\left(\frac{1}{2}\right)}^{\raisebox{1ex}{$1$}\!\left/ \!\raisebox{-1ex}{$2$}\right.} > {\left(\frac{1}{3}\right)}^{\raisebox{1ex}{$1$}\!\left/ \!\raisebox{-1ex}{$3$}\right.}$

• ${\left(\frac{1}{2}\right)}^{\raisebox{1ex}{$1$}\!\left/ \!\raisebox{-1ex}{$2$}\right.} < {\left(\frac{1}{3}\right)}^{\raisebox{1ex}{$1$}\!\left/ \!\raisebox{-1ex}{$3$}\right.}$

• ${\left(\frac{1}{2}\right)}^{\raisebox{1ex}{$1$}\!\left/ \!\raisebox{-1ex}{$2$}\right.} = {\left(\frac{1}{3}\right)}^{\raisebox{1ex}{$1$}\!\left/ \!\raisebox{-1ex}{$3$}\right.}$

• None of these

Out of 12 observations arranged in ascending order, the sixth and seventh observations are 14 and 15 respectively. Find the median of all the 12 observations.

• 29

• 14.5

• 15

• None of these 

Find the least number of square tiles required to pave the floor of a room 15 m 17 cm long and 9 m 2 cm broad

• 902

• 800

• 814

• None of these

A motor boat whose speed is 15 km/h in still water goes 36 km upstream and comes back to the starting point in 5 hours. Find the speed of the stream

• 5 km/h

• 10k/h

• Cant determine

• 3km/h