Probability 7th Grade Math

Front

What is probability?

Back

Probability is a measure of how likely an event is to occur, expressed as a number between 0 and 1, where 0 means the event will not happen and 1 means it will definitely happen.

Front

What is the probability of drawing a green marble from a jar containing 15 green, 25 red, and 10 blue marbles?

Back

The probability of drawing a green marble is 15/(15+25+10) = 15/50 = 3/10.

Front

If a jar contains 50 marbles (15 green, 25 red, 10 blue), what is the probability of NOT drawing a green marble?

Back

The probability of NOT drawing a green marble is 1 - P(green) = 1 - (15/50) = 35/50 = 7/10.

Front

What is the probability of drawing a red marble from a jar with 50 marbles?

Back

The probability of drawing a red marble is 25/(15+25+10) = 25/50 = 1/2.

Front

In a survey, if 40% of customers prefer drama books, how many drama books should a bookstore order if they plan to order 400 books?

Back

They should order 40% of 400, which is 0.4 * 400 = 160 books.

Front

What is the probability of rolling an EVEN number on a 6-sided die?

Back

The probability of rolling an EVEN number (2, 4, or 6) is 3/6 = 1/2.

Front

What is the probability of NOT rolling an EVEN number on a 6-sided die?

Back

The probability of NOT rolling an EVEN number (rolling 1, 3, or 5) is also 3/6 = 1/2.

Front

If George picks 64 apples and 2 out of every 16 have a worm, how many apples are expected to have a worm?

Back

Expected number of apples with a worm = (2/16) * 64 = 8 apples.

Front

If a coin is tossed 72 times, how many times do you expect to toss a head?

Back

You expect to toss a head 36 times, as the probability of heads is 1/2.

Front

What is a sample space in probability?

Back

A sample space is the set of all possible outcomes of a probability experiment.