Use a tree diagram to find the indicated probability.
-In the town of Cheraw,a certain type of laptop computer is sold at just two stores.Store A has 38% of the sales, 4% of which are of defective items,and store B has 62% of the sales,2% of which are of defective items.A
Person receives one of these laptop computers as a gift.What is the probability it is defective?
A)0.014
B)0.028
C)0.42
D)0.03

Question

Quizplus · Accepted Answer

The tree diagram would look like:
```
      /       \
   Store A   Store B
   /   \      /   \
Def.  OK   Def.  OK
  0.04 0.36 0.02 0.60
```
The probability of receiving a defective laptop computer is the sum of the probabilities of selecting a defective laptop computer from each store multiplied by their respective probabilities of choosing that store:
$(0.04)(0.38) + (0.02)(0.62) = 0.0148$
Round to two decimal places: 0.01 will go to 0, and then 0.48 will become 0.5 or 0.01 + 0.02 = 0.03. Hence, the probability it is defective is 0.028. Therefore, the best choice is B.

Use a Tree Diagram to Find the Indicated Probability