Answer:
(C)A matched-pairs design and a t-interval for a difference between means for independent samples.
Step-by-step explanation:
A matched-pairs design is a design technique that is used by researchers to compare two similar variables (objects or people).
In matched-pairs design, the two variables are splitted(divided into two) , one variable is placed in the treatment group and the other is placed in a control group.
Matched-pairs design is a design that helps to minimise and prevent the interference of external variables in the experiment.
In the question above, the experiment in the question utilises the used of a matched-pair design because we are comparing two similar objects together with is two footballs of similar size but one contains air while the other one contains helium.
The t-interval for inference used in this experiment(matched-pairs design) is a t-interval for a difference between means for independent samples.
