Question

hong wants to find the average height of students in the 10th grade at east high school. so he will use a sample of students in the 10th grade to find the average height.
answer the questions below.
(a) which unit(s) could be used for the unit of measurement? check all that apply.
□ minutes
□ feet
□ centimeters
□ inches
□ seconds
(b) which of the procedures below would be the best way to find the average height?
○ measure the heights of 3 volunteers from the 10th grade.
○ ask for 20 volunteers from the 10th grade to state their own heights.
○ randomly pick 3 students from the 10th grade and have them state their own heights.
○ randomly pick 20 students from the 10th grade and measure their heights.

Explanation:

(a) Units for height are length-based; minutes/seconds measure time, so they are invalid. Feet, centimeters, and inches are standard length units for measuring height.
(b) To get a reliable average, a random, adequately sized sample measured directly is best. A small sample of 3 is not representative, self-reported heights can be inaccurate, and volunteers may not represent the whole grade. A random sample of 20 measured directly is the most reliable method.

Answer:

(a)
☑ feet
☑ centimeters
☑ inches
☐ minutes
☐ seconds

(b)
☐ Measure the heights of 3 volunteers from the 10ᵗʰ grade.
☐ Ask for 20 volunteers from the 10ᵗʰ grade to state their own heights.
☐ Randomly pick 3 students from the 10ᵗʰ grade and have them state their own heights.
☑ Randomly pick 20 students from the 10ᵗʰ grade and measure their heights.