In a study of 250 adults, the mean heart rate was 70 beats per minute. Assume the population of heart rates is known to be appro
ximately normal with a standard deviation of 12 beats per minute. What is the 99% confidence interval for the mean beats per minute?
68.9 − 76.3
70 − 72
61.2 − 72.8
68 − 72
68.9 − 76.3
70 − 72
61.2 − 72.8
68 − 72
1 answer:
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The answer is 
.
Explanation:
In order to subtract the fractions, we must make them like fractions. To do this, the denominators must be the same by multiplying (only). Since the first fraction is
, 3 can be multiplied by 2 to get 6, which is the other fraction, we can multiply it. Whatever you do to the denominator you must do to the numerator. Now multiply 2 by the numerator (10) to get 
. Now we can subtract the fractions and 
to get 13/6. Since this fraction is not in mixed fraction form yet, we must do that first. goes into 13 twice, so the whole number is 2 and there is still 1 left, making the fraction 
. Therefore, the difference is 2 .
Explanation:
In order to subtract the fractions, we must make them like fractions. To do this, the denominators must be the same by multiplying (only). Since the first fraction is