A certain disease affects 1 in 1000 people. If a random sample of 2000 people is

A certain disease affects 1 in 1000 people. If a random sample of 2000 people is taken, how many are expected to be affected? (2021)

A certain disease affects 1 in 1000 people. If a random sample of 2000 people is taken, how many are expected to be affected? (2021)

Step 1: Understand that the disease affects 1 in 1000 people. This means for every 1000 people, 1 person is expected to have the disease.
Step 2: We have a sample of 2000 people. We need to find out how many people in this sample are expected to be affected by the disease.
Step 3: To find the expected number of affected people, we can use the formula: Expected number affected = Total number of people in the sample × (Probability of being affected).
Step 4: The probability of being affected is 1 in 1000, which can be written as 1/1000.
Step 5: Now, plug in the numbers: Expected number affected = 2000 × (1/1000).
Step 6: Calculate the result: 2000 × (1/1000) = 2.
Step 7: Therefore, in a random sample of 2000 people, we expect 2 people to be affected by the disease.

Probability and Expectation – Understanding how to calculate expected values based on probabilities.