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Worksheet: Samples and the Role of Randomness


Three different toys are stored in a warehouse. There are 15 000 toys in total and the number of each is shown in the table.

Kinds of Stones Bears Dolls Cars
Number of Stones 2 000 6 000 7 000

A stratified sample of all the toys is taken and 420 cars are selected. Calculate the total number of toys in the sample.


A class in a school contains 38 students. At the end of the school year 28 of the students passed mathematics, 32 passed science, and 26 passed both science and mathematics. If a student is chosen at random from the class, what is the probability that they failed science?

  • A
  • B
  • C
  • D
  • E


Which type of random sample should be used to determine the subject preferences of a group of 400 students given the ratio of males to females is ?

  • Astratified random sample
  • Bsimple random sample


Which type of random sample can be used to study the level of qualifications in a society divided into lower class, middle class and upper class?

  • Astratified random sample
  • B simple random sample


In what sort of sampling does the researcher divide the population into separate groups called strata, then draw a probability sample from each group?

  • Asystematic sampling
  • Bcluster sampling
  • Cmultistage sampling
  • Dstratified sampling
  • Esimple random sampling


Which type of random sample is used for selecting a sample from one strata of society?

  • Astratified random sample
  • B simple random sample


Which of the following choices would define a random experiment?

  • A It is an experiment or a process for which the outcome cannot be predicted with certainty.
  • B It is an experiment or a process for which the outcome can be predicted with certainty.


Which of the following is an outcome of a random experiment?

  • A rolling a pair of dice
  • B choosing two marbles from a jar
  • C flipping a coin
  • D landing the pointer of the spinner on the red color
  • E drawing a card from a pack of 52 cards