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Q:

Two dice are tossed. The probability that the total score is a prime number is:

A) 5/12	B) 1/6
C) 1/2	D) 7/9

Answer & Explanation Answer: A) 5/12

Explanation:

Clearly, n(S) = (6 x 6) = 36.

Let E = Event that the sum is a prime number.

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

n(E) = 15.

P(E) = n(E)/n(S) = 15/36 = 5/12.

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Filed Under: Probability

Q:

In 100 m race, A covers the distance in 36 seconds and B in 45 seconds. In this race A beats B by:

A) 20m	B) 25m
C) 22.5m	D) 9m

Answer & Explanation Answer: A) 20m

Explanation:

Distance covered by B in 9 sec. = (100/45)*9m = 20m

A beats B by 20 metres.

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Filed Under: Races and Games

Q:

In a race of 200 m, A can beat B by 31 m and C by 18 m. In a race of 350 m, C will beat B by:

A) 22.75 m	B) 25 m
C) 19.5 m	D) 18.5 m

Answer & Explanation Answer: B) 25 m

Explanation:

A : B = 200 : 169.

A : C = 200 : 182.

C/B = (C/A*A/B) = (182/200*200/169) = 182:169

When C covers 182 m, B covers 169 m.

When C covers 350 m, B covers (169/180*350)m = 325 m

Therefore, C beats B by (350 - 325) m = 25 m.

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Q:

From a pack of 52 cards, two cards are drawn together at random. What is the probability of both the cards being kings?

A) 1/15	B) 1/221
C) 25/57	D) 35/256

Answer & Explanation Answer: B) 1/221

Explanation:

Let S be the sample space

Then, n(S) = $52 C_{2}$ = 1326.

Let E = event of getting 2 kings out of 4.

n(E) = $\frac{52 * 51}{2 * 1}$ = 6.

$4 C_{2}$

=> $\frac{4 * 3}{2 * 1}$

$P (E) = \frac{n (E)}{n (S)} = \frac{6}{1326} = \frac{1}{221}$

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Q:

At a game of billiards, A can give B 15 points in 60 and A can give C to 20 points in 60. How many points can B give C in a game of 90?

A) 30 points	B) 20 points
C) 10 points	D) 12 points

Answer & Explanation Answer: C) 10 points

Explanation:

A : B = 60 : 45.

A : C = 60 : 40.

B/C = (B/A*A/C) = (45/60*60/45) = 45/40 = 90/80 = 90:80

B can give C 10 points in a game of 90.

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Filed Under: Races and Games

Q:

In a 100 m race, A beats B by 10 m and C by 13 m. In a race of 180 m, B will beat C by:

A) 5.4m	B) 4.5m
C) 5m	D) 6m

Answer & Explanation Answer: D) 6m

Explanation:

A : B = 100 : 90.

A : C = 100 : 87.

B/C = (B/A*A/C) = (90/100*100/87) = 30/29

When B runs 30 m, C runs 29 m.

When B runs 180 m, C runs (29/30*180)m =174m

B beats C by (180 - 174) m = 6 m.

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Filed Under: Races and Games

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

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