Hypothesis testing, binomial

Past records suggest that 30% of customers who buy baked beans from a large supermarket buy them in single tins. A new manager questions whether or not there has been a change in the proportion of customers who buy baked beans in single tins.

• Two-tailed test

• One-tailed test, on the left

• One-tailed test, on the right

Dhriti grows tomatoes. Over a period of time, she has found that there is a probability 0.3 of a ripe tomato having a diameter greater than 4 cm. She decides to try a new fertiliser. In a random sample of 40 ripe tomatoes, 18 have a diameter greater than 4 cm. Dhriti claims that the new fertiliser has increased the probability of a ripe tomato being greater than 4 cm in diameter.

• Two-tailed test

• One-tailed test, on the left

• One-tailed test, on the right

Linda regularly takes a taxi to work five times a week. Over a long period of time she finds the taxi is late once a week. The taxi firm changes her driver and Linda thinks the taxi is late more often. In the first week, with the new driver, the taxi is late 3 times.

• Two-tailed test

• One-tailed test, on the left

• One-tailed test, on the right

Past records from a large supermarket show that 20% of people who buy chocolate bars buy the family size bar. On one particular day a random sample of 30 people was taken from those that had bought chocolate bars and 2 of them were found to have bought a family size bar. Test at the 5% significance level, whether or not the proportion p, of people who bought a family size bar of chocolate that day had decreased. State your hypotheses clearly.

• Two-tailed test

• One-tailed test, on the left

• One-tailed test, on the right

A teacher thinks that 20% of the pupils in a school read the Deano comic regularly. He chooses 20 pupils at random and finds 9 of them read Deano. Test, at the 5% level of significance, whether or not there is evidence that the percentage of pupils that read Deano is different from 20%. State your hypotheses clearly.

• Two-tailed test

• One-tailed test, on the left

• One-tailed test, on the right

Brad planted 25 seeds in his greenhouse. He has read in a gardening book that the probability of one of these seeds germinating is 0.25. Ten of Brad’s seeds germinated. He claimed that the gardening book had underestimated this probability. Test, at the 5% level of significance, Brad’s claim. State your hypotheses clearly.

• Two-tailed test

• One-tailed test, on the left

• One-tailed test, on the right