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Worksheet: Using Probability to Calculate Expected Values

Q1:

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?

Q2:

A fair die is rolled 300 times. Calculate the expected number of times a prime number is rolled.

Q3:

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?

Q4:

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?

Q5:

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

Q6:

A factory produced 2 000 light bulbs each day. A sample of 500 bulbs were tested and 29 of them were defective. What is the expected number of non-defective bulbs produced in a day.

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 produces two types of shirts: A and B. A sample of 100 shirts from each of 5 shopping malls was observed to see how many of each type were sold. The results are shown in the table.

Number of Shopping Malls (1) (2) (3) (4) (5)
Sales of Type A 35 66 29 44 53
Sales of Type B 65 34 71 56 47

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

  • A
    1 980
  • B
    1 638
  • C
    1 020
  • D
    1 362
  • E
    2 130

Q9:

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?

Number 1 2 3 4 5 6
Rolls 23 17 15 10 2 11

Q10:

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?