4. Baby walkers are seats hanging from frames that allow babies to sit upright with their legs dangling and feet touching the floor. Walkers have wheels on their legs that allow the infant to propel the walker around the house long before he or she can walk or even crawl. Typically, babies use walkers between the ages of 4 months and 11 months. Because most walkers have tray tables in front that block babies' views of their feet, child psychologists have begun to question whether walkers affect infants' cognitive development. One study compared mental skills of a random sample of those who used walkers with a random sample of those who never used walkers. Mental skill scores averaged 113 for 54 babies who used walkers (standard deviation of 12) and 123 for 55 babies who did not use walkers (standard deviation of 15). (a) Is there evidence that the mean mental skill score of babies who use walkers is different from the mean mental skill score of babies who do not use walkers? Explain your answer. (b) Suppose that a study using this design found a statistically significant result. Would it be reasonable to conclude that using a walker causes a change in mean mental skill score? Explain your answer.
Permutations and Combinations
If there are 5 dishes, they can be relished in any order at a time. In permutation, it should be in a particular order. In combination, the order does not matter. Take 3 letters a, b, and c. The possible ways of pairing any two letters are ab, bc, ac, ba, cb and ca. It is in a particular order. So, this can be called the permutation of a, b, and c. But if the order does not matter then ab is the same as ba. Similarly, bc is the same as cb and ac is the same as ca. Here the list has ab, bc, and ac alone. This can be called the combination of a, b, and c.
Counting Theory
The fundamental counting principle is a rule that is used to count the total number of possible outcomes in a given situation.
parts a and b please show work
![4. Baby walkers are seats hanging from frames that allow babies to sit upright with their legs dangling and feet
touching the floor. Walkers have wheels on their legs that allow the infant to propel the walker around the house
long before he or she can walk or even crawl. Typically, babies use walkers between the ages of 4 months and
11 months.
Because most walkers have tray tables in front that block babies' views of their feet, child psychologists have
begun to question whether walkers affect infants' cognitive development. One study compared mental skills of
a random sample of those who used walkers with a random sample of those who never used walkers. Mental
skill scores averaged 113 for 54 babies who used walkers (standard deviation of 12) and 123 for 55 babies who
did not use walkers (standard deviation of 15).
(a) Is there evidence that the mean mental skill score of babies who use walkers is different from the mean
mental skill score of babies who do not use walkers? Explain your answer.
(b) Suppose that a study using this design found a statistically significant result. Would it be reasonable to
conclude that using a walker causes a change in mean mental skill score? Explain your answer.](/v2/_next/image?url=https%3A%2F%2Fcontent.bartleby.com%2Fqna-images%2Fquestion%2Fbca49413-148b-49bc-9aca-0999bd714989%2F14da9995-fa45-4ed7-88f0-0a5f3c3d65ff%2F8xmrijn_processed.jpeg&w=3840&q=75)
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