Unit 2 MSTAR-Style Practice Test — Form A

Understanding the World Around Us Through Statistics · 12 questions · English only, like the real test · No timer — take the time you need.

These are MSTAR-style questions written for this curriculum to rehearse the format. They are not official Maryland assessment items. MSTAR — Maryland's new state test, first given in spring 2027 — uses the same kinds of questions you see here: selected response, select-all, two-part evidence questions, and written responses.

How this works: Answer every question, then press Submit & Grade. Selected-response parts grade instantly with an explanation for each; written responses go to your teacher. Your answers save on this device.

On the real MSTAR: math runs as three 40-minute sessions, in English, on a computer. Here there is no clock — practice the thinking first; the pacing comes with rehearsal.

Written responses: how should the explain-the-error questions be scored?

Instant scoring checks whether your explanation states the value and uses the reasoning the question is about. It matches words and numbers, so a right answer worded differently can score low — your teacher can always re-score it from the answer key.

16.DS.1Understand Statistical Questions

Select all that apply

Select ALL questions that are statistical questions:

How tall is each player on the team? How many hours per week do sixth graders spend reading? What is my shoe size? How long does it take students in our class to get to school? What is the capital of Maryland?

26.DS.5Represent and Describe Data in a Histogram

Part A

A histogram uses intervals 0–9, 10–19, 20–29, and 30–39. A data value of 19 belongs in which interval?

10–19 0–9 20–29 It belongs in two intervals.

Part B

Why are the bars of a histogram drawn with no gaps between them?

Gaps would make the histogram too wide. The intervals are continuous, so the bars show one unbroken range of values. Histograms always use exactly four bars. The bars represent categories that must touch.

36.DS.4Describe the Data Using the Median

Explain the error

Kai found the median of 14, 22, 9, 30, 18. He wrote: 'The middle number written down is 9, so the median is 9.'

Explain Kai's misconception and give the correct median.

✍️ Written response — 2 points.

46.DS.5Represent and Describe Data in a Box Plot

Select all that apply

Select ALL statements that are true about box plots:

The 5-number summary is minimum, Q1, median, Q3, and maximum. The box spans from Q1 to Q3. The line inside the box is the median. The whiskers show the mean of each half. IQR = Q3 − Q1.

56.DS.3Describe Data by Range and Interquartile Range

Part A

Two classes have the same median score of 81. Class A scores range from 78 to 84; Class B scores range from 60 to 99. What does this tell you?

Class B has a higher median. Class B has greater variability, even though the centers are the same. Class A has more students. The two classes performed identically.

Part B

Why is the IQR often preferred over the range as a measure of spread?

The IQR is always larger than the range. The range cannot be calculated for large data sets. The IQR uses every value in the data set. The range depends on only two values and is strongly affected by an outlier.

66.NOS.2Divide Multi-Digit Numbers Using an Algorithm

Explain the error

Andre computed 618 ÷ 3. He wrote: '6 ÷ 3 = 2, then 1 ÷ 3 does not go so I skip it, then 8 ÷ 3 = 2 remainder 2. My answer is 22 remainder 2.'

Explain Andre's misconception and give the correct quotient.

✍️ Written response — 2 points.

76.NOS.3Divide Decimals Using an Algorithm

Part A

Find 18.9 ÷ 6.3 using the decimal division algorithm.

0.3 2.8 3 30

Part B

Why does sliding BOTH decimal points the same number of places leave the quotient unchanged?

The decimal point does not affect division. Only the divisor matters in a division problem. The quotient always doubles when you slide a point. Multiplying the dividend and the divisor by the same power of ten produces an equivalent division.

86.DS.4Describe Data Using the Mean

Part A

Find the mean of this data set: 6, 10, 14, 8, 12.

8 10 12 50

Part B

The mean is often described as a 'fair share' or a balance point. Why?

The mean is always the middle value when ordered. The mean is the value that occurs most often. The mean is halfway between the minimum and maximum. If the total were redistributed equally among all the values, each would receive the mean.

96.DS.6cDescribe Data by Mean Absolute Deviation

Explain the error

Sofia found the MAD of 3, 5, 9, 11 (mean 7). She used the signed differences −4, −2, 2, 4, added them to get 0, and concluded 'the MAD is 0, so there is no variability.'

Explain Sofia's misconception and give the correct MAD.

✍️ Written response — 2 points.

106.DS.6dChoose Appropriate Measures

Select all that apply

Select ALL statements that correctly guide the choice of measures:

Skewed data with outliers is better summarized by the median and IQR. Symmetric data with no outliers is well summarized by the mean and MAD. The mean is resistant to outliers. An outlier affects the range more than it affects the IQR. The shape of the distribution should influence which measures you report.

116.NOS.3Add and Subtract Decimals

Part A

Find 12.4 + 3.75.

4.99 15.15 16.15 16.79

Part B

Why is a placeholder zero written as 12.40 rather than leaving 12.4?

It changes the value of 12.4 to make the addition work. Zeros must always be written at the end of a decimal. It makes both numbers have the same number of decimal places so each column holds the same place value. It rounds the answer to the nearest hundredth.

126.NOS.3Multiply Decimals

Part A

Find 2.4 × 0.5.

0.12 1.2 12 120

Part B

How is the number of decimal places in the product determined?

Use the number of decimal places in the larger factor. Multiply the number of decimal places in the two factors. Add the number of decimal places in the two factors. The product always has one decimal place.