Question

Box contains the following numbered tickets: 1,1,5,9,9 a) If I draw two tickets with replacement, what is the chance that the sum of the two tickets is greater than or equal to 10?

Answer 1

17/25

Explanation:

The probability of drawing 1 = 2/5

The probability of drawing 5 = 1/5

The probability of drawing 9 = 2/5

Since the sum of the two ticket is greater than or equal to 10,

If I draw 1 first, I can only only select 9 also= 2/5* 2/5

= 4/25

If I draw 5, I can draw another 5 or 9 later = 1/5 * (1/5+2/5)

= 1/5 * 3/5

= 3/25

If I draw 9 then I can draw anything

2/5 * 5/5

= 10/25

The sum of all the products = 4/25 + 3/25 + 10/25

= 17/25