HSSC CLERK EXAM (21.09.2019)

41. A man buys oranges at Rs. 5 a dozen and an equal number at Rs. 4 a dozen. He sells them at Rs. 5.50 a dozen and makes a profit of Rs. 50. How many oranges does he buy?

(1) 30 dozens
(2) 40 dozens
(3) 50 dozens
(4) 60 dozens

Correct Answer: (3) 50 dozens

Solution:C.P. of 2 dozens of oranges = Rs. 9

Their S.P. = Rs. (2 × 5.50) = Rs. 11

∴Profit = (11 - 9) = Rs. 2

When profit = Rs. 2, oranges bought = 2 dozens

For a profit of Rs. 50

Oranges bought = 50 dozens

42. The average of 17 numbers is 10.9 and if the average of first nine numbers is 10.5 and that of the last nine numbers is 11.4. The middle number is

(1) 11.8
(2) 11.4
(3) 10.9
(4) 11.7

Correct Answer: (1) 11.8

Solution:Ninth number

= 9 × 10.5 + 9 × 11.4 - 17 × 10.9

= 94.5 + 102.6 - 185.3

= 197.1 - 185.3 = 11.8

43. If 6m = 46656, what is the value of 6m-2 ?

(1) 7776
(2) 7782
(3) 1296
(4) 1290

Correct Answer: (3) 1296

Solution:

∴ 46656 = 2⁶ × 3⁶ = (6)⁶

∴ 6ᵐ = 6⁶ ⇒ m = 6

∴ 6ᵐ⁻² = 6⁶⁻² = 6⁴ = 1296

44. The value of [(10)¹⁵⁰÷(10)¹⁴⁶] is

(1) 1000
(2) 10000
(3) 100000
(4) 10⁶

Correct Answer: (2) 10000

Solution:

45. Pipes A and B can fill a tank in 5 hours and 6 hours respectively. Pipe C can empty it in 12 hours. If all the three pipes are opened together, then the tank will be filled in

(1) 24/5
(2) 60/17
(3) 22/5
(4) 58/17

Correct Answer: (2) 60/17

Solution:When all three pipes are opened together, part of tank filled in 1 hour

= 1/5 + 1/6 - 1/12

= (12 + 10 - 5)/60 = 17/60

∴ Required time = 60/17 Hours

= 60/17 Hours

46. Who invented the Air-plane?

(1) Waterman
(2) Oscar
(3) Wilson
(4) Wright brothers

Correct Answer: (4) Wright brothers

Solution:The Wright brothers - Or. ville and Wilbur were two American aviation pioneers generally credited with inventing, building, and flying the world's first successful airplane. They made the first controlled, sustained flight of a powered, heavier than air aircraft with the Wright Flyer on December 17, 1903 near North Carolina.

47. Sound travels fastest through

(1) Vacuum
(2) Steel
(3) Water
(4) Air

Correct Answer: (2) Steel

Solution:Sound travels fastest through solids. This is because molecules in a solid medium are much closer together than those in a liquid or gas, allowing sound waves to travel more quickly through it. In fact, sound waves travel over 17 times faster through steel than through air.

48. Which of the following constituents of pollutant exhaust is hazardous to man?

(1) Carbon monoxide
(2) Carbon dioxide
(3) Lead particles
(4) Carbon particles

Correct Answer: (2) Carbon dioxide

Solution:Exhaust pollutants comprise poisonous chemicals such as carbon monoxide, sulfur dioxide, nitrogen oxides, formaldehyde, benzene, etc, that can be detrimental to the human body if consistently inhaled in large quantities. Among them, carbon monoxide is the most hazardous as it binds to the hemoglobin in our blood, which results in suffocation and even death.

49. Which of the following combination of chromosomes is present in males?

(1) XX
(2) XXX
(3) XY
(4) ΧΥΧ

Correct Answer: (3) XY

Solution:Males typically have two different kinds of sex chromosomes (XY), and are called the heterogametic sex. In humans, the presence of the Y chromosome is responsible for triggering male development; in the absence of the Y chromosome, the fetus will under go female development.

50. What is the main component of bones and teeth?

(1) Calcium carbonate
(2) Calcium phosphate
(3) Calcium sulphate
(4) Calcium nitrate

Correct Answer: (2) Calcium phosphate

Solution:Calcium phosphate is the main chemical substance present in the bones and teeth of animals. Seventy percent of bone consists of hy droxyapatite, a calcium phosphate mineral (known as bone mineral). Tooth enamel is composed of almost ninety percent hydroxyapatite.