Grade 9 · Statistics & probability

Statistics basics practice

Statistics basics is a grade 9 math skill aligned to Common Core standard HSS.ID.A.2: use statistics appropriate to the shape of the data distribution to compare center (median, mean) and spread (interquartile range, standard deviation) of two or more different data sets. Below are 8 practice questions with answers and step-by-step explanations, drawn from the 25 statistics basics problems our math games drill.

CCSS HSS.ID.A.225 questions in the bank

Sample questions

Try 8 for free

Question 1easy

Find the mean of $4, 7, 10$ .

Mean $= \dfrac{4 + 7 + 10}{3} = \dfrac{21}{3} = 7$ .

Question 2easy

Find the median of $3, 7, 9$ .

When ordered least to greatest: $3, 7, 9$ . The middle value is $7$ .

Question 3easy

What is the mode of $2, 2, 6, 8, 9$ ?

The mode is the most frequent value; $2$ appears twice while every other value appears once.

Question 4easy

Find the range of $12, 7, 15, 3, 9$ .

Range $=$ maximum $-$ minimum $= 15 - 3 = 12$ .

Question 5easy

A runner logged the miles she ran on seven consecutive days: $3, 5, 4, 6, 5, 7, 5$ . What is the mean number of miles per day?

Mean $= \dfrac{3 + 5 + 4 + 6 + 5 + 7 + 5}{7} = \dfrac{35}{7} = 5$ miles per day.

Question 6easy

Find the mean of $5, 10, 15$ .

Mean $= \dfrac{5 + 10 + 15}{3} = \dfrac{30}{3} = 10$ .

Question 7easy

Find the median of $12, 5, 8$ .

When ordered least to greatest: $5, 8, 12$ . The middle value is $8$ .

Question 8easy

A coach records the goals her team scored in seven games: $1, 3, 2, 3, 0, 3, 2$ . What is the mode of the data?

The value $3$ appears three times, more often than any other value, so the mode is $3$ .

Tests that cover statistics basics:

NAEP ACT PSAT 8/9 VTCAP NC EOG/EOC

More Grade 9 skills:

Discriminant analysis Compound inequality situations Equivalent rational expressions (SAT)Problem solving in context (SAT)Common factor factoring (SAT)Evaluating functions at a value Interpreting data displays Absolute value equations All Grade 9 practice →

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