1) The probability of getting at least one tail in 5 throws of a coin is?

a)1/32 b)31/32 c)1/5 d)None of the above

Ans. a coin throws 5 times is equal to the 5 coins throws at one time.

So total no of choices are 25=32

Chances that not getting at least one tails is 1 i.e., (h,h,h,h,h)

So 1-(1/32)=31/32…option (b) is correct.

2) When a local train travels at a speed of 60kmph, it reaches the destination on time. When the same train travels at speed of 50kmph, it reaches its destination 15 minutes late. What is the length of journey?

a)75km b)50km c)60km d)85km

Ans. let the time taken by a train to reach destination at 60kmph is x. Then it takes (x+15) at 50kmph.

So distance, 60x=50(x+15)

X=75…option (a) is correct.

3)Give the greatest pair of twin primes which are below 100?

a)71,73 b)93,95 c)97,99 d)87,89

Ans. in the given options only 71 and 73 are primes.

## Answers & Comments

Answer:AMCAT Quantitative Ability Previous Papers-1

1) The probability of getting at least one tail in 5 throws of a coin is?

a)1/32 b)31/32 c)1/5 d)None of the above

Ans. a coin throws 5 times is equal to the 5 coins throws at one time.

So total no of choices are 25=32

Chances that not getting at least one tails is 1 i.e., (h,h,h,h,h)

So 1-(1/32)=31/32…option (b) is correct.

2) When a local train travels at a speed of 60kmph, it reaches the destination on time. When the same train travels at speed of 50kmph, it reaches its destination 15 minutes late. What is the length of journey?

a)75km b)50km c)60km d)85km

Ans. let the time taken by a train to reach destination at 60kmph is x. Then it takes (x+15) at 50kmph.

So distance, 60x=50(x+15)

X=75…option (a) is correct.

3)Give the greatest pair of twin primes which are below 100?

a)71,73 b)93,95 c)97,99 d)87,89

Ans. in the given options only 71 and 73 are primes.

So option (A) is correct.

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