Need help with 7 and 8 (explanation how I got the answers)

Mathematics

1 answer:

rewona [7]4 years ago

3 0

I think you are to add then divide by 3 hope I helped a little

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Sound travels about 750 miles per hour. If you stand in a canyon and sound a horn, you will hear an echo.

cricket20 [7]

Answer:

The sound takes time to go to a point and reflect back to your position.

It means the sound went twice a distance.

=> Suppose it takes about 0.5 seconds to hear the echo, the canyon wall would be [750 x (0.5/3600)]/2 = 0.052 miles

=> Suppose it takes about n seconds to hear the echo, the canyon wall would be [750 x (n/3600)]/2 miles

Hope this helps!

8 0

3 years ago

IQ scores are known to be normally distributed. The mean IQ score is 100 and the standard deviation is 15. What percent of the p

Masja [62]

Answer:

47.06% of the population has an IQ between 85 and 105.

Step-by-step explanation:

Problems of normally distributed samples are solved using the z-score formula.

In a set with mean $\mu$ and standard deviation $\sigma$ , the zscore of a measure X is given by:

$Z = \frac{X - \mu}{\sigma}$

The Z-score measures how many standard deviations the measure is from the mean. After finding the Z-score, we look at the z-score table and find the p-value associated with this z-score. This p-value is the probability that the value of the measure is smaller than X, that is, the percentile of X. Subtracting 1 by the pvalue, we get the probability that the value of the measure is greater than X.

In this problem, we have that:

$\mu = 100, \sigma = 15$