a)
To verify: If the normal model can be used to describe the possible number of heads in 250 spins.
Yes, the normal model can be used to describe the number of heads in 250 spins.
Given:
The probability of heads when a coin is tossed
The total number of coin spins
The number of heads observed
Concept used:
A probability distribution where each trial has two possible outcomes known as a success and failure, each trial is independent and the probability of each trial is the same, then to calculate the probability of a certain number of successes occurring, a binomial probability distribution is used. A binomial model can be approximated to be a normal model if it satisfies the following conditions
Calculation:
The total number of coin spins
The probability of heads for a fair coin
The conditions to assume normal model are satisfied as shown below
Conclusion:
The conditions are satisfied, thus the number of heads in 250 spins can be assumed to be normally distributed.
b)
To calculate: The mean and standard deviation of the number of heads.
The mean and standard deviation of the number of heads is 125 and 7.9057 respectively.
Concept used:
The mean and standard deviation of the binomial model is calculated as shown below
Calculation:
The total number of coin spins
The probability of heads for a fair coin
The mean and standard deviation are calculated as shown below
Conclusion:
The mean and standard deviation for the distribution of the number of heads is 125 and 7.9057 respectively
c)
To calculate: Whether the outcome of 140 heads is statistically significant.
The outcome of 140 heads is not statistically significant.
Concept used:
The Z score, the number of standard deviations away from the mean is calculated using the formula
High values of the Z score (above 2 or less than -2) are usually considered less likely to occur and statistically significant.Calculation:
The probability of heads when a coin is tossed
The total number of coin spins
The number of heads observed
The Z score is calculated as shown below
Conclusion:
The Z score of 1.897 is not high and not unusual. Thus the outcome of 140 heads is not statistically significant.
Chapter 10 Solutions
PRECALCULUS:GRAPHICAL,...-NASTA ED.
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