National Benchmark Tests (NBT) · Quantitative Literacy

Data, averages and probability

21 practice questions, each with the answer and an explanation.

Practise Data, averages and probability now

Random questions from this topic, one at a time. You see the answer and the explanation straight after each one.

All 21 questions

  1. A learner's marks in 5 tests are 69, 84, 72, 65, 80. What mark is needed in the next test for the average of all 6 tests to be 70?
  2. A learner's marks in 5 tests are 73, 80, 56, 55, 53. What mark is needed in the next test for the average of all 6 tests to be 65?
  3. A learner's marks in 4 tests are 74, 76, 69, 63. What mark is needed in the next test for the average of all 5 tests to be 70?
  4. A learner's marks in 4 tests are 65, 70, 81, 82. What mark is needed in the next test for the average of all 5 tests to be 65?
  5. A learner's marks in 5 tests are 85, 78, 76, 70, 69. What mark is needed in the next test for the average of all 6 tests to be 70?
  6. A learner's marks in 4 tests are 68, 61, 67, 62. What mark is needed in the next test for the average of all 5 tests to be 65?
  7. A learner's marks in 6 tests are 76, 51, 83, 65, 64, 84. What mark is needed in the next test for the average of all 7 tests to be 70?
  8. A learner's marks in 4 tests are 77, 50, 73, 61. What mark is needed in the next test for the average of all 5 tests to be 70?
  9. A bag holds 4 red, 4 blue and 2 green marbles. One marble is taken at random. What is the probability that it is red?
  10. A bag holds 6 red, 2 blue and 2 green marbles. One marble is taken at random. What is the probability that it is red?
  11. A bag holds 3 red, 5 blue and 2 green marbles. One marble is taken at random. What is the probability that it is red?
  12. A town's population was 800 in 2015 and 1000 in 2020. By what percentage did the population change between the two years?
  13. A town's population was 900 in 2015 and 720 in 2020. By what percentage did the population change between the two years?
  14. A town's population was 1200 in 2015 and 1500 in 2020. By what percentage did the population change between the two years?
  15. A town's population was 500 in 2015 and 650 in 2020. By what percentage did the population change between the two years?
  16. A town's population was 2500 in 2015 and 2000 in 2020. By what percentage did the population change between the two years?
  17. In a survey of 500 learners, 3/10 of them walk to school. How many learners walk to school?
  18. In a survey of 240 learners, 3/8 of them walk to school. How many learners walk to school?
  19. In a survey of 480 learners, 1/4 of them walk to school. How many learners walk to school?
  20. In a survey of 300 learners, 2/5 of them walk to school. How many learners walk to school?
  21. In a survey of 360 learners, 5/6 of them walk to school. How many learners walk to school?

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