Lesson Worksheet: Prediction Using Probability Mathematics • 7th Grade

In this worksheet, we will practice predicting the actions of a larger group using a sample and finding the expected value.

Q1:

The probability that a biased die will land on an even number is 0.6. If the die is rolled 80 times, how many times is it expected to land on an even number?

Q2:

Jacob plays a card game with his friend and the result can be either win, lose, or draw. Each time they play, the probability that Jacob will win is 0.5, and the probability he will lose is 0.3. If they play 50 games, what is the expected number that will end in a draw?

Q3:

The table shows the results of rolling a die 78 times. Using this information, how many times is the number 2 expected to appear if the die is rolled 234 times?

Q4:

A factory produces two types of shirts: A and B. The table shows how many shirts of each type were sold in 5 samples of 100 shirts from 5 different shopping malls.

Shopping Mall(1)(2)(3)(4)(5)
Sales of Type A3566294453
Sales of Type B6534715647

If the factory sells 3,000 shirts, how many of them do you expect to be of type A?

Q5:

A random sample of 80 school students were asked to vote for their preferred sport and the results are shown in the table. If the whole school contains 700 students, how many are expected to prefer football?

GameFootballBasketballTable TennisSwimming
Number of Students3224816

Q6:

A survey of 80 students found that 40 students preferred biology, 24 preferred chemistry, and 16 preferred physics. If there are 200 students in the whole school, how many are expected to prefer biology based on the results of the survey?

Q7:

A factory produces 8,000 shirts each day. At the end of a day, 1,600 shirts were inspected and 50 were found to be defective. What is the expected number of defective shirts produced that day?

Q8:

A factory produced 1,600 calculators in one day. They took a sample of those calculators and found that 3% were defective. What is the expected number of defective calculators produced that day?

Q9:

In a survey of 400 tourists who visited Egypt, 160 were from Arab countries, 120 were from Europe, 40 from Latin America, and 80 from Australia. If the total number of tourists who visited Egypt in a month was 5,000, how many of them are expected to be from Europe?

Q10:

The probability of a cow contracting an illness at a farm is 0.17. If there are 1,800 cows at the farm, what is the expected number of infected cows?

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