A large group of students took a test in Physics and the final grades have a mean of 70 and a standard deviation of 10. If we can approximate the distribution of these grades by a normal distribution, between what two scores of the test in the middle 95%?

The scores are between 50 and 90

Step-by-step explanation:

When we say middle 95%, we means that this value falls between 2 standard deviations of the mean i.e

μ ± 2σ

Hence,

mean of 70 and a standard deviation of 10

μ ± 2σ

μ - 2σ

70 - (2 × 10)

= 70 - 20

= 50

μ + 2σ

= 70 + (2 × 10)

= 70 + 20

= 90

1) is right

step-by-step explanation:

fist on the left goes with the third on the right. second on the left goes with the fourth on the right. third on the left goes with the second on the right. the fourth on the left goes with first on the right