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Grade 12

Using z-scores to Identify Probabilities

Interactive practice questions

The table below shows the area under the standard normal curve between $0$0 and a given $z$z-score. Use this table to find the probability that a variable has a $z$z-score less than $z=0.85$z=0.85.

Give your answer to four decimal places.

A z-table showing z values.
Easy
2min

The average life span of a tortoise is estimated to be approximately $100$100 years, with a standard deviation of $7$7 years.

Use the table below showing the area under the standard normal curve between $0$0 and a given $z$z-score to answer the following questions.

Easy
3min

A sprinter is training for a national competition. She runs 400 m in an average time of $75$75 seconds, with a standard deviation of $6$6 seconds.

Use the table below showing the area under the standard normal curve between $0$0 and a given $z$z-score to answer the following questions.

Easy
4min

Research scientists have measured the heights of a large number of eucalyptus trees in an area of forest. The average height of these trees is $60$60 m, with a standard deviation of $6$6 m.

Use the table below showing the area under the standard normal curve between $0$0 and a given $z$z-score to answer the following questions.

Easy
3min
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Outcomes

12D.B.2.8

Recognize a z-score as the positive or negative number of standard deviations from the mean to a value of the continuous random variable, and solve probability problems involving normal distributions using a variety of tools and strategies, including problems arising from real-world applications

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