If two dice are thrown together, the probability of getting an even number on one die and an odd number on the other is__________?

If two dice are thrown together, the probability of getting an even number on one die and an odd number on the other is__________?

A. 1/4
B. 1/2
C. 3/4
D. 3/5
The number of exhaustive outcomes is 36.
Let E be the event of getting an even number on one die and an odd number on the other. Let the event of getting either both even or both odd then = 18/36 = 1/2
P(E) = 1 – 1/2 = 1/2.

Out of first 20 natural numbers, one number is selected at random. The probability that it is either an even number or a prime number is_____________?

Out of first 20 natural numbers, one number is selected at random. The probability that it is either an even number or a prime number is_____________?

A. 1/2
B. 16/19
C. 4/5
D. 17/20
Explanation:
n(S) = 20
n(Even no) = 10 = n(E)
n(Prime no) = 8 = n(P)
P(EᴜP) = 10/20 + 8/20 – 1/20 = 17/20

If a number is chosen at random from the set {1, 2, 3, …., 100}, then the probability that the chosen number is a perfect cube is___________?

If a number is chosen at random from the set {1, 2, 3, …., 100}, then the probability that the chosen number is a perfect cube is___________?

A. 1/25
B. 1/2
C. 4/13
D. 1/10
Explanation:
We have 1, 8, 27 and 64 as perfect cubes from 1 to 100.
Thus, the probability of picking a perfect cube is
4/100 = 1/25.

The probability that a number selected at random from the first 50 natural numbers is a composite number is__________?

The probability that a number selected at random from the first 50 natural numbers is a composite number is__________?

A. 21/25
B. 17/25
C. 4/25
D. 8/25
Explanation:
The number of exhaustive events = ⁵⁰C₁ = 50.
We have 15 primes from 1 to 50.
Number of favourable cases are 34.
Required probability = 34/50 = 17/25.

Three taps A, B and C can fill a tank in 12, 15 and 20 hours respectively. If A is open all the time and B and C are open for one hour each alternately, the tank will be full in_________?

Three taps A, B and C can fill a tank in 12, 15 and 20 hours respectively. If A is open all the time and B and C are open for one hour each alternately, the tank will be full in_________?

A. 6 hours
B. 6 2/3 hours
C. 7 hours
D. 7 1/2 hours

A cistern can be filled by a tap in 4 hours while it can be emptied by another tap in 9 hours. If both the taps are opened simultaneously, then after how much time will the cistern get filled?

A cistern can be filled by a tap in 4 hours while it can be emptied by another tap in 9 hours. If both the taps are opened simultaneously, then after how much time will the cistern get filled?

A. 4.5 hrs
B. 5 hrs
C. 6.5 hrs
D. 7.2 hrs

A large tanker can be filled by two pipes A and B in 60 minutes and 40 minutes respectively. How many minutes will it take to fill the tanker from empty state if B is used for half the time and A and B fill it together for the other half?

A large tanker can be filled by two pipes A and B in 60 minutes and 40 minutes respectively. How many minutes will it take to fill the tanker from empty state if B is used for half the time and A and B fill it together for the other half?

A. 15 min
B. 20 min
C. 27.5 min
D. 30 min