Organizing 30 Test Scores

Pre-Algebra · Axiom Academy

EXAMPLE Organizing 30 Test Scores into a Frequency Table Group raw data into intervals, count the frequencies, and read the distribution. A Pre-Algebra teacher records the scores of all 30 students on a test. As one long list, the numbers are hard to make sense of. Organize them into a frequency table so the class's performance becomes clear. Thirty separate numbers — too many to see a pattern at a glance. Choose an interval width of 10 Scores run from the 60s to the 90s, so four equal-width intervals of 10 cover them cleanly: Tally each score into its interval The frequencies add back to the 30 scores we started with: 4 + 10 + 9 + 7 = 30 . Each bar's height is its frequency. The tallest bar is 70–79; the heights step down on either side. Most common range: 70–79 holds 10 students — one third of the class ( ). Shape: scores cluster in the middle (70s and 80s) and thin out toward the low 60s and high 90s. Spread: every score falls between 65 and 96, covering all four intervals. Overall: 16 of 30 students scored 80 or above ( ). Nice work — you turned 30 loose scores into a frequency table and read the story behind them. Pick a sensible interval width: 10 points splits 0–100 test scores into a handful of clear groups — not so wide it hides detail, not so narrow it scatters. Tally, then count: sort each score into its interval and the frequencies fall out; they must add back to the total ( 4 + 10 + 9 + 7 = 30 ).

This is the written version of the interactive lesson above. See the full Pre-Algebra course.