A score of 60 is 2 standard deviations below the mean (80 -2·10 = 60). The empirical rule tells you that 95% of the distribution is within 2 standard deviations of the mean. The remaining 5% is split evenly between those that are more than 2 SD above the mean and those that are more than 2 SD below the mean.

That tells you the percentage who failed is about 2.5%. The best answer choice is 2%.

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<em>Additional comment</em>

The empirical rule is a little bit sloppy, but it gets you in the ballpark. The actual percentage is closer to 2.275%.

6 0

2 years ago

Please Help! My question is in the picture.

Varvara68 [4.7K]

First we need to determine the type of progression in the question.
That's geometric progression. Because the pattern from one sequence to the others are about multiplying.

Second, determine the ratio of the progression
r = a₂/a₁
r = a₂ ÷ a₁
r = 1/2 ÷ 2
r = 1/2 × 1/2
r = 1/4

Third, determine the formula to know the recursive rule
a₂ = a × 1/4
a₂ = 1/4 × a
$a_{n} = \frac{1}{4} a_{(n-1)}$

Fourth, determine a₁. a₁ is the first term of the progression
a₁ = 2

Final answer:
Recursive rule
$a_{n} = \frac{1}{4} a_{(n-1)}$
a₁ = 2

4 0

3 years ago