Facespace is a popular form of social media. recent reports
show that the mean time spent on facespace is 40 minutes a
day with a standard deviation of 6 minutes a day. the data is
normally distributed.
if 3900 people are on in one sitting, how many of them lie
within one standard deviation below the mean and
two standard deviations above the mean?

3192 persons! ✔️

Step-by-step explanation:

From the statement, we know that μ = 40 [minutes] and σ = 6 [minutes]

There are 3900 people. And we need to find how many of the lie within one standard deviation below the mean and two standard deviations above the mean.

We need to find the probability between: 34 minutes and 52 minutes. With the help of a calculator we get that the probability is: P(34<z<52) = 0.8186

Therefore, 0.8186×3900 = 3192 persons! ✔️

d, x=8

step-by-step explanation:

simplifying

4x + -5 = 2x + 11

reorder the terms:

-5 + 4x = 2x + 11

reorder the terms:

-5 + 4x = 11 + 2x

solving

-5 + 4x = 11 + 2x

solving for variable 'x'.

move all terms containing x to the left, all other terms to the right.

add '-2x' to each side of the equation.

-5 + 4x + -2x = 11 + 2x + -2x

combine like terms: 4x + -2x = 2x

-5 + 2x = 11 + 2x + -2x

combine like terms: 2x + -2x = 0

-5 + 2x = 11 + 0

-5 + 2x = 11

add '5' to each side of the equation.

-5 + 5 + 2x = 11 + 5

combine like terms: -5 + 5 = 0

0 + 2x = 11 + 5

2x = 11 + 5

combine like terms: 11 + 5 = 16

2x = 16

divide each side by '2'.