Question

Forty lottery tickets numbered 1,2,3..are put in a bag. Two draws of one ticket are made the ticket after the first draw is replaced. What is the probability that in the first draw it is a multiple of 4or 5 and in the second it is a multiple of 5

Answer 1

Answer: 0.085

Explanation P(A) - first draw

Multiple of 4:- 10/40

I.e. 4,8,12,16,20,24,28,32,36,40

Multiple of 5:- 8/40

I.e. 5,10,15,20,25,30,35,40

Probability of first draw= multiple of 4+ multiple of 5 - common multiple

10/40+8/40-1/40

Probability of first draw= 17/40

Probability of second draw -P(B)

Multiple of 5 :- 8/40

Probability of first and second draw= P(A) *P(B)

=17/40*8/40

=136/1600

=0.085.

Hope this helps!

Answer 2

When forty lottery tickets numbered 1,2,3.. are put in a bag and draws are made the probability that in the first draw it is a multiple of 4 or 5 and in the second it is a multiple of 5 is 0.08.

1. Let

P(4 or 5) be the probability of getting a multiple of 4 or 5

P(4) be the probability of getting a multiple of 4 =10/40

P(5) be the probability of getting a multiple of 5 =8/40

P(4&5) be the probability of getting a multiple of 4 and 5 =2/40

2. P(4 or 5) = P(4)+ P(5)- P(4&5) =10/40 +8/40 -2/40 =16/40

3. P(4 or 5) in first draw and P(5) in second draw =P(4 or5) ×P(5) = (16/40)×(8/40) =2/25 =0.08