Lesson: Prediction Using Probability

A sample of 330 people was taken to study the level of education of members in a society. If the ratio of males to females in the sample is , find the number of males in the sample.

A school has 500 students; 320 of them are boys. To select students for a survey, a stratified sample of 25 students will be taken. How many boys and how many girls will be selected by the sample?

A factory produces 3 different models of cars every year: 673 of the first model, 514 of the second model, and 213 of the third model. If the manager wants to select a sample of of all the cars for inspection, how many cars will be in the sample?

A random sample of 80 school students were asked to vote for their preferred sport and the results are shown in the table. If the whole school contains 700 students, how many are expected to prefer football?

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 based on the results of the survey?

The table shows the results from a survey where 20 students from a school were asked to pick their favorite fruit from 3 options. By calculating the experimental probability that a student’s favorite fruit is an orange, calculate how many of the 400 students in the school, would choose an orange as their favorite.

Fruit	Apple	Banana	Orange
Number of Students	10	2	8

A student wants to research the amount of pocket money students in his middle school receive.

Which of the following would be the best way to get a representative sample of the population?

A company wants to survey its employees to measure job satisfaction. The company has 300 employees, and the management wants of the employees to participate. Determine the number of the employees who will participate.

A factory owner wishes to conduct a survey of 675 employees. The owner wants a sample size of . How many employees will be in the sample?

Which of the following will give a representative sample?

A sixth-grade boy is considering joining the school choir. He wonders how many boys sing in the choir. In the choir brochure, there is a photo showing 10 boys and 13 girls. Assuming the photo is representative of the choir and given that the choir has 70 singers in total, what would be a possible estimate of the number of boys in the choir from this photo?

There are 1 000 employees work at a company. The manager wishes to conduct a survey and needs to ask a sample of of the employees. Determine the number of employees who will participate.

A sample of 96 people was taken to study the level of education of members in a society. If the ratio of males to females in the sample is , find the number of males and females in the sample.

A large fast-food chain wants to find out if its customers like their new salad range. They conduct a survey where they interview 3 000 customers in their Texas restaurants.

What is the sample of the population?

The numbers of students of a university in the first, second, third, and fourth years are 1 000, 5 000, 8 000, and 6 000 respectively. Given that 700 students were selected randomly to participate in a contest and the number of students selected from each year is proportional to the total number of students in that year, how many third-year students were selected?

A drug company conducted a trial to find out if migraine symptoms in females, aged 25 to 40, lessened after they took a new drug. The people in the trial found that the number of migraines they experienced was halved.

Which of the following inferences would the company make from their results?

A manufacturer of energy-saving light bulbs claims that the lifespan of their bulbs is between 10 000 and 15 000 hours. Is this figure a sample statistic or a population characteristic?

Victoria makes a random selection of 40 students from her school to investigate how the students at her high school feel about the quality of food in the school canteen.

What is the population that has been sampled?

A principal wishes to conduct a survey at their school. There are 400 students at the school, and the principal wants of them to participate in the survey. Determine the number of students who will participate.

A manufacturing company is to conduct a survey of the 1 000 employees at its factory. The management wants of the employees to participate. Determine the number of employees who will participate.

An animal rescue center wants to find out if people in their town think more money should be spent on animal welfare. They plan to ask a random sample of their visitors and volunteers to fill in a questionnaire.

Why would their sample not be representative of the town’s population?

There are about 15 million registered voters in a state, and the government wants to know what proportion of them intends to vote in the next general election. In a survey of registered voters, 848 responded that they did intend to vote.

Which of the following is the population parameter?