Probability question

[omega]

A fast-food restaurant has determined that eh chance that a customer will order a soft drink is 0.90. The chance that a
customer will order a hamburger is 0.60. The chance that a customer will order French Fries is 0.50. Round answer to 3
decimal points

A. If a customer places an order, what is the probability that the order will include a soft drink and no fries if these two
events are independent?

B. The restaurant has also determined that if a customer orders a hamburger the change the customer will also order fries is
0.80. Determine the probability that the order will include a hamburger and fries.

[quark]

a. Since they are independent, P(soft drink and fries)=P(soft drink)*P(fries)=0.9*0.5=0.45

P(soft drink and NO fries)=P(soft drink) - P(soft drink and fries)

b.
P(fries|hamburger)=0.8

Since P(fries|hamburger)=P(fries and hamburger)/P(hamburger)
0.8=P(fries and hamburger)/0.6
You can solve for p.