Probability Quiz Set 005 | Maths Aptitude Quiz Questions and Mock Test on Probability Set 5 | mock tests for Bank PO, SSC Exams, SO Clerical Exam, GATE Exam, LIC AO, GIC AO, etc.

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Question 1

A box contains 5 maroon, 4 pink and 8 sky blue balls. What is the probability of drawing a ball that is neither pink nor maroon?

${8/17}$.

$9/17$.

$9/136$.

$13/136$.

Soln.
Ans: a

Total number of marbles is 17. We have to basically find the probability of picking a sky blue ball, for which 8 chances are favorable. So probability = 8/17 = ${8/17}$.

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Question 2

9 bowls are lying inverted on a table. 2 of them contain prizes, but 7 of them are empty. What is the probability of getting a prize if one of the bowls is opened randomly?

${2/9}$.

$3/9$.

$4/9$.

$7/9$.

Soln.
Ans: a

Chances favoring a prize are 2, whereas the total chances are 9. The probability is 2/9 = ${2/9}$.

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Question 3

A bag contains 2 Red, 8 Blue and 7 Green marbles. What is the probability of drawing a Red marble if 2 marbles are drawn out randomly?

${31/136}$.

$7/17$.

$32/136$.

$36/136$.

Soln.
Ans: a

Total number of marbles is 17. Combinations of 2 marbles that are possible = ¹⁷C₂ = ${17 × 16}/2$ = 136. If one of the two balls is red, then red + red is one possibility, and 2 × (8 + 7) are the other possibilities. So total favorable outcomes = 1 + 2 × 15 = 31, and the probability is 31/136 = ${31/136}$.

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Question 4

From a deck of 52 cards two cards are drawn at random. What is the probability that both will be "10"?

${1/221}$.

$9/15$.

$2/221$.

$6/221$.

Soln.
Ans: a

Number of ways of drawing 2 cards out of 52 = ⁵²C₂ = $(52 × 51)/2$ = 1326. There are 4 "10"s in all, so 2 can be drawn in ⁴C₂ = $(4 × 3)/2 = 6$ ways. The probability is 6/1326 = ${1/221}$.

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Question 5

A box contains 3 pink, 4 maroon and 6 orange marbles. What is the probability of drawing a orange marble if 2 marbles are drawn out randomly?

${19/26}$.

$6/13$.

$20/78$.

$24/78$.

Soln.
Ans: a

Total number of marbles is 13. Combinations of 2 marbles that are possible = ¹³C₂ = ${13 × 12}/2$ = 78. If one of the two balls is orange, then both balls will be orange in ⁶C₂ = ${6 × (6 - 1)}/2$ = 15 ways. The number of ways in which non-orange can be drawn out are 6 × (3 + 4). So total favorable outcomes = 15 + 6 × 7 = 57, and the probability is 57/78 = ${19/26}$.

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