Chapter 5: Q 61. (page 311)

Crawl before you walk (3.2) At what age do babies learn to crawl? Does it take longer to learn in the winter, when babies are often bundled in clothes that
restrict their movement? Perhaps there might even be an association between babies’ crawling age and the average temperature during the month they first try to crawl (around six months after birth). Data were collected from parents who brought their babies to the University of Denver Infant Study Center to participate in one of a number of studies. Parents reported the birth month and the age at which their child was first able to creep or crawl a distance of four feet within one minute. Information was obtained on $414$ infants ( $208$ boys and $206$ girls). Crawling age is given in weeks, and average temperature (in °F) is given for the month that is six months after the birth month. $8$ Analyze the relationship between average crawling age and average temperature. What do you conclude about when babies learn to crawl?

Short Answer

Expert verified

The negative correlation between average temperature and average crawling age.

Step by step solution

Step 1. Given Information

If you're measuring rain fall, there could be mistakes owing to things like rainfall, human error, pollution, and so on that you're not measuring. i.e., if only 50 shrimp are used to calculate average weight, this 50 shrimp represents a small portion of the entire picture.

Step 2. Concept Used

Definition of the probability addition theorem: Assume A and B are two events in a random experiment, and you want to know whether A or B has a higher likelihood. Then apply the probability addition theorem.

Step 3. Explanation

The data:

We need to construct a scatter plot to understand the link between them. Using Microsoft Excel,

As a result, the average temperature and average crawling age have a negative relationship. In other words, if average temperature rises, so does average crawling age, and vice versa.