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Q:

In a 500 m race, the ratio of the speeds of two contestants A and B is 3 : 4. A has a start of 140 m. Then, A wins by:

A) 60m	B) 40m
C) 20m	D) 10m

Answer & Explanation Answer: C) 20m

Explanation:

To reach the winning post A will have to cover a distance of (500 - 140)m, i.e., 360 m.

While A covers 3 m, B covers 4 m.

While A covers 360 m, B covers (4/3)*360 = 480 m.

Thus, when A reaches the winning post, B covers 480 m and therefore remains 20 m behind.

A wins by 20 m.

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Filed Under: Races and Games

Q:

A and B take part in 100 m race. A runs at 5 kmph. A gives B a start of 8 m and still beats him by 8 seconds. The speed of B is:

A) 5.15 kmph	B) 4.14 kmph
C) 4.25 kmph	D) 4.4 kmph

Answer & Explanation Answer: B) 4.14 kmph

Explanation:

A's speed = (5*5/15)m/sec = (25/18)m/sec

Time taken by A to cover 100 m = (100*18/15)sec = 72sec

Time taken by B to cover 92 m = (72 + 8) = 80 sec.

B's speed =(92/80*18/5)kmph =4.14kmph

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Filed Under: Races and Games

Q:

In a lottery, there are 10 prizes and 25 blanks. A lottery is drawn at random. What is the probability of getting a prize?

A) 2/7	B) 5/7
C) 1/5	D) 1/2

Answer & Explanation Answer: A) 2/7

Explanation:

Total number of outcomes possible, n(S) = 10 + 25 = 35

Total number of prizes, n(E) = 10

$P (E) = \frac{n (E)}{n (S)} = \frac{10}{35} = \frac{2}{7}$

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Filed Under: Probability

Q:

In a class, there are 15 boys and 10 girls. Three students are selected at random. The probability that 1 girl and 2 boys are selected, is:

A) 21/46	B) 1/5
C) 3/25	D) 1/50

Answer & Explanation Answer: A) 21/46

Explanation:

Let , S - sample space E - event of selecting 1 girl and 2 boys.

Then, n(S) = Number ways of selecting 3 students out of 25

= $25 C_{3}$

= 2300.

n(E) = $10 C_{1} \times 15 C_{2}$ = 1050.

$\therefore$ P(E) = n(E)/n(s) = 1050/2300 = 21/46

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Filed Under: Probability

Q:

In a class, there are 15 boys and 10 girls. Three students are selected at random. The probability that 1 girl and 2 boys are selected, is:

A) 21/46	B) 1/5
C) 3/25	D) 1/50

Answer & Explanation Answer: A) 21/46

Explanation:

Let S be the sample space and E be the event of selecting 1 girl and 2 boys.

Then, n(S) = Number ways of selecting 3 students out of 25

= $25 C_{3}$ = 2300.

n(E)= $10 C_{1} * 15 C_{2}$ = 1050.

P(E) = n(E)/n(s) = 1050/2300 = 21/46

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Filed Under: Probability

Q:

Two dice are thrown simultaneously. What is the probability of getting two numbers whose product is even?

A) 3/4	B) 3/8
C) 5/16	D) 2/7

Answer & Explanation Answer: A) 3/4

Explanation:

In a simultaneous throw of two dice, we have n(S) = (6 x 6) = 36.

Then, E= {(1, 2), (1, 4), (1, 6), (2, 1), (2, 2), (2, 3), (2, 4), (2, 5), (2, 6), (3, 2), (3,4),(3, 6), (4, 1), (4, 2), (4, 3), (4, 4), (4, 5), (4, 6), (5, 2), (5, 4), (5, 6), (6, 1),6, 2), (6, 3), (6, 4), (6, 5), (6, 6)}

n(E) = 27.

P(E) = n(E)/n(S) = 27/36 = 3/4.

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Filed Under: Probability

Q:

Three unbiased coins are tossed. What is the probability of getting at most two heads?

A) 3/4	B) 7/8
C) 1/2	D) 1/4

Answer & Explanation Answer: B) 7/8

Explanation:

Here S = {TTT, TTH, THT, HTT, THH, HTH, HHT, HHH}

Let E = event of getting at most two heads.

Then E = {TTT, TTH, THT, HTT, THH, HTH, HHT}.

P(E) =n(E)/n(S)=7/8.

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Filed Under: Probability

Q:

What would be the least number of years in which the simple interest on Rs.2600 at % will be an exact number of rupees ?

A) 2	B) 3
C) 4	D) 5

Answer & Explanation Answer: B) 3

Explanation:

$S . I = R s . [2600 * \frac{20}{3} * \frac{1}{100} * t]$

$S . I = R s . [\frac{520}{3} * t]$

t=3

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Filed Under: Compound Interest
Exam Prep: Bank Exams
Job Role: Bank PO

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