Given : The long-distance calls made by the employees of a company are normally distributed with a mean of 6.3 minutes and a standard deviation of 2.2 minutes

i.e. $\mu = 6.3$ minutes

$\sigma=2.2$ minutes

Let x be the long-distance call length.

a. The probability that a call lasts between 5 and 10 minutes will be :-

$P(5$

b. The probability that a call lasts more than 7 minutes. :

$P(X>7)=P(\dfrac{X-\mu}{\sigma}>\dfrac{7-6.3}{2.2})\\\\=P(Z>0.318)\ \ \ \ [z=\dfrac{X-\mu}{\sigma}]\\\\=1-P(Z$

c. The probability that a call lasts more than 4 minutes. :

$P(X$

8 0

3 years ago

What is the axis of symmetry of the function f(x)= -(x+9)(x-21)

Vinil7 [7]

Answer:

The axis of symmetry is x = 6

Step-by-step explanation:

To find this, first find the two x-intercept values and then take the average. This will always be the line of symmetry.

x + 9 = 0

x = -9

x - 21 = 0

x = 21

Now take the average of these two numbers.

(-9 + 21)/2

12/2

6 0

3 years ago