Answer:
b=5
Step-by-step explanation:
2+b=7
Subtract 2 from each side
2+b-2=7-2
b= 5
This is how you add fractions..
I have solved it step-by-step. If you understand this, you'll know how to subtract, too.
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Using the Empirical Rule, it is found that her finishing time will be between 70 and 82 seconds in 95% of her races.
<h3>What does the Empirical Rule state?</h3>
It states that, for a normally distributed random variable:
- Approximately 68% of the measures are within 1 standard deviation of the mean.
- Approximately 95% of the measures are within 2 standard deviations of the mean.
- Approximately 99.7% of the measures are within 3 standard deviations of the mean.
In this problem, the mean is of 76 seconds and the standard deviation is of 3 seconds, then:
76 - 2 x 3 = 70.
76 + 2 x 3 = 82.
Which means that values between 70 and 82 seconds are within 2 standard deviations of the mean, hence the percentage is of 95%.
More can be learned about the Empirical Rule at brainly.com/question/24537145
