Question

what is the width of the class interval for the plot below?
reaction time difference (msec)
a. 20
b. 25
c. 50
d. 24

Explanation:

Step1: Identify class bounds

Take the first class: 25-49.

Step2: Calculate interval width

Subtract lower from upper bound: $49 - 25 + 1 = 25$
(Note: For discrete data, we add 1 to account for both endpoints; for continuous, it is $49 - 25 = 24$, but standard class interval width for this bin labeling uses the difference of upper and lower limits of consecutive bins, e.g., $50 - 25 = 25$)

Answer:

b. 25