Mehmet is a developmental psychologist who wants to test the claims that a company's video series can help babies learn language faster than normal. Mehmet collects a sample of babies and has them participate in a program where they watch the video series over the course of 9 months. His data are shown. Use the data in the table to answer the following questions.

Sample size	200
Proportion that received language training outside this study	12%
Average age at the start of the study	10.45 months
Average age of first spoken word	12.5 months
Average vocabulary size by 18 months	56.3 words
Proportion that scored above average on vocabulary test at the end of study	51%

1. Name the type of variable used to measure age in this study. Explain your answer.
2. Name the type of variable used to measure the number of babies that scored higher than average on a vocabulary test in this study. Explain your answer.
3. Mehmet knows that the average vocabulary size of a typical 18-month-old is about 50 words. The standard deviation is about 6 words. What is the probability that the sample of 200 18-month-olds in this study would have a vocabulary size that is as high as it was?
4. Mehmet decides to look only at the babies who had not received language training outside the study. He found that they had an average vocabulary size of 50.3 words at 18 months of age. What is the probability that this sample would have a vocabulary size that is 50.3 words?