Each time Caroline goes shopping she decides whether or not to buy fruit. The probability that she does buy fruit is 0.4.
Independently, she then decides whether or not to buy a CD, with a probability of 0.3 that she does buy a CD.
Work out the probability that she buys fruit or buys a CD or both.

 0.58

Step-by-step explanation:

Step 1 : Caroline buys fruit and buys cd ( buys both) = 0.12      ( 0.4 x 0.3)

Step 2 : Caroline buys fruit and not cd =  0.28                          ( 0.4 x 0.7)

Step 3 : Caroline doesn't buy fruit but buys cd = 0.18               ( 0.6 x 0.3 )

STEP 4 (FINAL STEP) : Add all the probabilities ( 0.12 + 0.28 + 0.18)

0.58

Step-by-step explanation:

Step 1 : Caroline buys fruit and buys cd ( buys both) = 0.12      ( 0.4 x 0.3)

Step 2 : Caroline buys fruit and not cd =  0.28                          ( 0.4 x 0.7)

Step 3 : Caroline doesn't buy fruit but buys cd = 0.18               ( 0.6 x 0.3 )

STEP 4 (FINAL STEP) : Add all the probabilities ( 0.12 + 0.28 + 0.18)

ANSWER =  0.58

to add: align your decimal and add just like you would regualar 2 or more digit numbers

To subtract: Write down the two numbers, one under the other, with the decimal points lined up. Add zeros so the numbers have the same length. Then subtract normally, remembering to put the decimal point in the answer.

To multiply: Multiply normally, ignoring the decimal points. Then put the decimal point in the answer - it will have as many decimal places as the two original numbers combined