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MAT-144 · In-person sections Exam 3 Review · Unit 3
Exam 3 Review · Q14

Constructing a frequency distribution for non-grouped data

Tally a list into a table of counts. Easy marks, provided you check the counts sum back to the number of observations.

01 Worked Example Video
▸ VIDEO COMING SOON

A short walkthrough explaining what you need to know and how to solve this question type lands here once it's recorded.

02 What This Looks Like on ALEKS

ALEKS randomizes the numbers each attempt, but the question shape stays the same. Here are three example versions you might see.

Reading off the distribution

Twenty patients, distribution: F 3, M 6, P 4, T 3, W 4.

The Coast medical group contains doctors M, P and W. How many patients saw a Coast doctor?

A smaller group

Same distribution: F 3, M 6, P 4, T 3, W 4.

The Plymouth group contains P and T. How many patients saw a Plymouth doctor?

Everyone else

Same distribution: F 3, M 6, P 4, T 3, W 4.

How many patients did not see Dr Mitchel?

Heads up: Your ALEKS version will use different numbers. The numbers in the practice below are different too — that way you're exercising the move, not memorizing one answer.
03 The Rule
one row per distinct value, not per observation count how many times each appears
the frequencies must total the sample size the single check that catches a miscount
Work through the list once, marking a tally against each value as you meet it, rather than scanning the whole list separately for each category. One pass, no double counting. Then add the frequencies and confirm they come to the number of observations you were given.
Common slips
(1) Counted the same entry twice. Scanning repeatedly is how that happens; one pass with tallies does not. (2) Skipped a value with frequency zero. If a category exists but never appears, it still gets a row, with 0. (3) Did not check the total. Twenty observations means the frequencies add to 20, every time.
04 Practice — Step by Step
One pass, then check

A clinic has five doctors: Foster, Mitchel, Philips, Tran and Washington. Twenty patients were seen this morning, each by one doctor:

M W P F M   F P T M T   W W M W M   P M P T F

Step 1

Count Mitchel

How many patients saw Dr Mitchel (M)?
Step 2

Count Washington

How many saw Dr Washington (W)?
Step 3

Check the total

The full distribution is F 3, M 6, P 4, T 3, W 4. What do the frequencies add to?
▸ Related Mini Lessons
Q13 Q15
MAT-144 · EXAM 3 REVIEW · Q14 OF 20