John comes across a recent survey and wants to gauge the strength of the results.

Mathematics

1 answer:

Nata [24]3 years ago

6 0

Answer:

A margin of error of +/- 3%

Step-by-step explanation:

Strenght of surveys:

The lesser the margin of error, the more precise, stronger, the confidence interval is.

The margin of error depends of the number of people surveyed. The more people are surveyed, lower the margin of error is, giving a stronger interval.

In this question:

We want the smaller margin of error, which is given by:

A margin of error of +/- 3%

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Suppose you randomly guess on every question of a 20 question True/False test. Let x = number of questions that you answer corre

castortr0y [4]

Answer:

18.14% probability that you would get at least 12 questions correct.

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:

$\mu = 10, \sigma = 2.2$