This is solved using the probability distribution formula for random variables where the combination formula for selection is used to determine the probability of these random variables occurring. This formula is denoted by:

P(X=r) = nCr × p^r × q^n-r

Where:

n = number of sampled variable which in this case = 21

r = variable outcome being determined which in this case = 5

p = probability of success of the variable which in this case = 0.31

q= 1- p = 1 - 0.31 = 0.69

P(X=5) = 21C5 × 0.31^5 × 0.69^16

P(X=5) = 0.0241

4 0

3 years ago

Your friend sells half her stock of keyrings every hour. She has 24 boxes at the of the sale. How many boxes will she have left

Law Incorporation [45]

At 0 hours: 24 boxes
After 1 hour: 24/2 = 12 boxes
After 2 hours: 12/2 = 6 boxes
After 3 hours: 6/2 = 3 boxes

She will have 3 boxes after 3 hours.

Hope this helps :)

5 0

3 years ago