The mean hours of sleep that students get per night is 5 hours, the standard deviation of hours of sleep is 1 hour, and the distribution is approximately normal. complete the following sentence. for about 68% of students, nightly amount of sleep is between hours. for about 95% of students, nightly amount of sleep is between hours. for about 99.7% of students, nightly amount of sleep is between hours.

.For about 68% of students, nightly amount of sleep is between __4____and ___6__ hours.For about 95% of students, nightly amount of sleep is between __3____and __7___ hours.For about 99.7% of students, nightly amount of sleep is between ___2___and __8___ hours.                    

Step-by-step explanation:

The empirical rule tells us that for normal distributions,

68% of data lie within one standard deviation of the mean.

Thus, 68% of data lie within

⇒ 5 ± 1 = (4, 6) hours

Similarly, 95% of data lie within two standard deviation of the mean.

Thus, 95% of data lie within

⇒ 5 ± 2 = (3, 7) hours

99.7% of data lie within one standard deviation of the mean.

Thus, 99.7% of data lie within

⇒ 5 ± 3 = (2, 8) hours

f(x) = x^3 -2x^2 -3x

x( x^2 -2x-3)

x( x^2 +x -3x -3)

x( x(x+1) -3(x+1))

x( x-3)( x+1)

so zeroes are 0, 3,-1

its (2) option