- #1
Shackleford
- 1,656
- 2
Homework Statement
[/B]
Relative frequencies of amount purchased and method of payment
Cash Credit Debit
$<20 .09 .03 .04
$20-$100 .05 .21 .18
>$100 .03 .23 .14(a) What proportion of purchases are paid for in cash?
(b) Given that a purchase is for more than $100, what is the probability that it is paid for by credit?
(c) Are payment by credit and amount > $100 independent events?
Homework Equations
Conditional probability, independence, etc.
The Attempt at a Solution
(a) .09 + .05 + .03 = .17
(b) P(credit | >$100) = P(credit ∩ >$100)/P(>$100) = .23/.40 = .575
(c) Independent if P(credit ∩ >$100) = P(credit)P(>$100) = .23.
P(credit)P(>$100) = 0.47*0.40 = .188. not independent.Does that look right?
Last edited: