Suppose that 14 children, who were learning to ride two-wheel bikes, were survey

Question

Suppose that 14 children, who were learning to ride two-wheel bikes, were surveyed to determine how long they had to use training wheels. It was revealed that they used them an average of eleven months with a sample standard deviation of four months. Assume that the underlying population distribution is normal.

Part (a)

(i) Enter an exact number as an integer, fraction, or decimal.

x = 11

(ii) Enter an exact number as an integer, fraction, or decimal.

sx = 4

(iii) Enter an exact number as an integer, fraction, or decimal.

n = 14

(iv) Enter an exact number as an integer, fraction, or decimal.

n 1 = 13

Part (b)

Define the random variable X in words.

The mean amount of time a single child uses training wheels.The amount of time a single child uses training wheels.    The mean length of time for training wheels usage from a sample of 14 children.The population mean amount of time for training wheels usage for children.

Part (c)

Define the random variable

X

in words.

The mean amount of time a single child uses training wheels.The amount of time a single child uses training wheels.    The mean length of time for training wheels usage from a sample of 14 children.The population mean amount of time for training wheels usage for children.

Part (d)

Which distribution should you use for this problem? (Enter your answer in the form z or tdf where df is the degrees of freedom.)


Explain your choice.

The Student's t-distribution for 13 degrees of freedom should be used because we do not know the population standard deviation.

I don't understand what part d is asking can someone help? I've missed it on the last 2 questions

Explanation / Answer

b)

The population mean amount of time for training wheels usage for children

d)

Student t distribution should be used because population sd is not given and sample size is less than 30.

df = n-1=13

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