Final answer:
The normal time for Charlene Brewster's operation, given her average times and a performance rating of 85%, is 9.94 seconds, which is calculated by finding the mean of her times and then adjusting for her performance rating.
Step-by-step explanation:
To calculate Charlene Brewster's normal time for an operation when given times of (8.3, 8.7, 8.2) and (8.4, 8.7, 8.4) in seconds and a performance rating of 85%, we need to determine the average time and then adjust for her performance rating. The average time, often also referred to as the mean, is calculated by adding up the times and dividing by the number of observations. In this case, we add the six observed times together and divide by six.
The calculated average time is then divided by the performance rating to find the normal time. To adjust for the performance rating, we divide by the performance percentage expressed as a decimal. For an 85% performance rating, we divide by 0.85.
Let's compute the average time first:
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- Sum of times = 8.3 + 8.7 + 8.2 + 8.4 + 8.7 + 8.4 = 50.7 seconds
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- Number of observations = 6
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- Average time = 50.7 / 6 = 8.45 seconds
To find the normal time, we now adjust for the performance rating: