1. Making Inferences from Random Samples

2. Making Inferences
A shipment to a warehouse consists of 3,500 MP3 players. The manager chooses a random sample of 50 MP3 players and finds that 3 are defective. How many MP3 players in the shipment are likely to be defective ? Defective MP3s in sample = Defective MP3s in population size of sample size of population 3/50 = x/3500 3/50 = .6 10,500 = 50x or .6(3500) = = x

3. Making Inferences 3/30 = x/120 3/30 = .01
A manager samples the receipts of every fifth person who goes through the line Out of 50 people, 4 had a mispriced item. If 600 people go to this store each day, how many people can we expect to have a mispriced item ?
4/50 = x/ /50 = .08
2400 = 50x or (600) = 48
48 = x
Terry randomly selects 30 boxes of crayons from the shelf and finds 3 boxes with
a few broken crayons. If there are 120 boxes of crayons on the shelf, how many
would you expect to have broken crayons?
3/30 = x/ /30 = .01
360 = 30x or (120) = 12
12 = x

4. Making Inferences
Part of the population of 9,500 crocodiles at the Everglades National Park are nesting. A random sample of 60 crocodiles shows that 12 of them are nesting. Estimate the number of crocodiles expected to be nesting. 12/60 = x/9,500 12/60 = ,000 = 60x or .2(9,500) = 1,900 1,900 = x