Final answer:
Alli can indeed use time of day and noise level as variables to determine how long it takes her baby sister to fall asleep, as these factors can influence sleep onset. She should consistently record this data over a period of time for accurate results.
Step-by-step explanation:
True, if Alli wants to determine the time it takes for her baby sister to fall asleep, she might indeed use the time of day and noise level as variables in her experiment. These variables might affect the baby's sleep onset. For instance, the baby might fall asleep faster at certain times of the day or in a quieter environment. Monitoring these variables can provide Alli with valuable data about her sister's sleep pattern. It is crucial, however, that she records this information consistently and accurately over a certain period for her observations to be valid.
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