Generating Random Samples

Warm Up

1. If you assume the samples are representative, how many whole-wheat bagels might you infer are sold at each store?

2. Rank the samples for the shops in terms of how representative they are likely to be. Explain your rankings.

3. Which sample or samples should Maureen use to tell her managers how many whole-wheat bagels to make each day? Explain.

• Random samples can be generated to simulate problems by rolling number cubes or using a random number generator.

• Picking numbered pieces of paper from a hat can simulate random samples.

When generating a random sample, can the same value appear more

than once?

Yes; since a random sample is one where every value has an equal

chance of being selected, then any value in the range, even one

already selected, could be selected.

Allison buys 1000 hair clips for $275 without knowing that 160 of the clips are broken. She selects a random sample of 100

clips to predict how many clips will be broken in all. The random numbers in the chart represent her sample. If Allison wants to make a profit of at least $225 by selling all the non-broken clips, what is the lowest price Allison can charge per

clip?

Exit TicketCarter orders 120 glass ornaments online without knowing that 16 ornaments in the order are cracked. He decides to

test a random sample of 20 ornaments to predict the number of cracked ornaments in the order.

1. How many random numbers should be generated to simulate this problem?

2. Explain which randomly generated numbers should represent cracked ornaments, and which randomly generated numbers should represent non-cracked ornaments.

3. How many cracked ornaments would Carter expect to find in the order based on this sample: 60, 5, 99, 88, 61, 19, 57, 50, 21, 49, 78, 94, 80, 2, 109, 14, 79, 41, 90, 114? Explain.