The length of time students needed in order to complete a statistics test followed a distribution that was approximately normal. The mean was 74 minutes, the standar deviation was 8 minutes. What proportion of students took more than one hour to complete the test?

And we can find this probability on this way:

And using the normal standard distribution table or excel and we got:

Step-by-step explanation:

Let X the random variable that represent the length of time student of a population, and for this case we know the distribution for X is given by:

Where and

We are interested on this probability

We can solve the problem using the z score formula given by:

If we apply this formula to our probability we got this:

And we can find this probability on this way:

And using the normal standard distribution table or excel and we got:

answer:

c. the third graph

37/3

step-by-step explanation:

step 1: simplify both sides of the equation.

7x+8(x+

1

4

)=3(6x−9)−8

7x+(8)(x)+(8)(

1

4

)=(3)(6x)+(3)(−9)+−8(distribute)

7x+8x+2=18x+−27+−8

(7x+8x)+(2)=(18x)+(−27+−8)(combine like terms)

15x+2=18x+−35

15x+2=18x−35

tep 2: subtract 18x from both sides.

15x+2−18x=18x−35−18x

−3x+2=−35

step 3: subtract 2 from both sides.

−3x+2−2=−35−2

−3x=−37

step 4: divide both sides by -3.

−3x

−3

=

−37

−3

x=

37

3