The life span of the battery can be expected 98% of the batteries to meet the guarantee will be 149.3 hours.
<h3>What is the z-score?</h3>
The z-score is a statistical evaluation of a value's correlation to the mean of a collection of values, expressed in terms of standard deviation.
The z-score is given as
z = (x - μ) / σ
Where μ is the mean, σ is the standard deviation, and x is the sample.
Many electronic devices use disposable batteries, which eventually have to be replaced.
The mean is 140 hours and the standard deviation is 4 hours.
The marketing department wants to write a guarantee for the battery life.
The life span of the battery can be expected 98% of the batteries to meet the guarantee will be
Then the z value for 98% is 2.326.
Then the life span will be
2.326 = (x - 140) / 4
9.304 = x - 140
x = 149.3 hours
The life span of the battery can be expected 98% of the batteries to meet the guarantee will be 149.3 hours.
More about the z-score link is given below.
brainly.com/question/15016913
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Answer:
Square is the correct answer
Gretchen walked more than a whole mile on both days combined, because if on Saturday she walked 7/10 miles, she would have only needed 3/10 of a mile more to walk on Sunday to make 1 mile. On Sunday, however, she walked 3/4 miles, and using common knowledge, we know that 3/4 miles is more than 3/10. Thus, Gretchen walked more than a mile on both days combined.
