Question: 11 -

The total number of events of throwing 10 coins simultaneously is

100

512

10

1024

Answer:

1024

Solution:

Total events 2¹⁰ = 1024

Question: 12 -

What will be the value of P(not E) if P(E) = 0.07?

72

93

007

90

Answer:

93

Solution:

If the probability of happening of an event P(E) and that of not happening is P(E), then

P(E) + P(not E) = 1

So, P(not E) = 1 - P(E)

Since P(E) = 0.07

P(not E) = 1 - 0.07

P(not E) = 0.93

Question: 13 -

A number is selected at random from first 50 natural numbers. Then the probability that it is a multiple of 3 and 4 is:

7/50

4/25

1/25

2/25

Answer:

2/25

Solution:

The numbers that are multiple of 3(from first 50 natural numbers) are:

3, 6, 9, 12, 15, 18………………..48

The numbers that are multiple of 4 (from first 50 natural numbers) are:

4, 8, 12, 16…………………….48

The numbers that are multiples of 3 and 4 both are the multiples of 3×4=12 as both 3 and 4 are co-prime.

So common multiples are:

12, 24, 36, 48

Therefore probability is:

P (multiple of 3 and 4) = 4/50

⇒ P (multiple of 3 and 4) = 2/25

Question: 14 -

Cards bearing numbers 3 to 20 are placed in a bag and mixed thoroughly. A card is taken out from the bag at random. The probability that the number on the card taken out is an even number, is

1/3

1/20

1/4

1/2

Answer:

1/2

Solution:

Total cards = 18
Cards with even numbers are 4, 6, 8, 10, 12, 14, 16, 18, 20 = 9
∴ P(even number) =918=12

Question: 15 -

A number x is chosen at random from the numbers -2, -1, 0 , 1, 2. Then the probability that x² < 2 is?

4/5

2/5

1/5

3/5

Answer:

3/5

Solution:

We have 5 numbers −2,−1,0,1,2

Whose squares are 4,1,0,1,4

So square of 3 numbers is less than 2

Therefore Probability is:

P (x² < 2) = 3/5