# Worksheet: Samples and the Role of Randomness

Q1:

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 Number of Stones Bears Dolls Cars 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.

Q2:

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

Q3:

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

Q4:

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

Q5:

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

Q6:

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

• Astratified random sample
• B simple random sample

Q7:

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.

Q8:

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