Find the radius of a circle that has an area of 12.56 cm².

16. A telemarketer makes six phone calls per hour and is able to make a sale on 30% of these contacts. During the next two hours

Reika [66]

Answer:

a) 23.11% probability of making exactly four sales.

b) 1.38% probability of making no sales.

c) 16.78% probability of making exactly two sales.

d) The mean number of sales in the two-hour period is 3.6.

Step-by-step explanation:

For each phone call, there are only two possible outcomes. Either a sale is made, or it is not. The probability of a sale being made in a call is independent from other calls. So we use the binomial probability distribution to solve this question.

Binomial probability distribution

The binomial probability is the probability of exactly x successes on n repeated trials, and X can only have two outcomes.

$P(X = x) = C_{n,x}.p^{x}.(1-p)^{n-x}$

In which $C_{n,x}$ is the number of different combinations of x objects from a set of n elements, given by the following formula.

$C_{n,x} = \frac{n!}{x!(n-x)!}$

And p is the probability of X happening.

A telemarketer makes six phone calls per hour and is able to make a sale on 30% of these contacts. During the next two hours, find:

Six calls per hour, 2 hours. So

$n = 2*6 = 12$

Sale on 30% of these calls, so $p = 0.3$

a. The probability of making exactly four sales.

This is P(X = 4).

$P(X = x) = C_{n,x}.p^{x}.(1-p)^{n-x}$

$P(X = 4) = C_{12,4}.(0.3)^{4}.(0.7)^{8} = 0.2311$

23.11% probability of making exactly four sales.

b. The probability of making no sales.

This is P(X = 0).

$P(X = x) = C_{n,x}.p^{x}.(1-p)^{n-x}$

$P(X = 0) = C_{12,0}.(0.3)^{0}.(0.7)^{12} = 0.0138$

1.38% probability of making no sales.

c. The probability of making exactly two sales.

This is P(X = 2).

$P(X = x) = C_{n,x}.p^{x}.(1-p)^{n-x}$

$P(X = 2) = C_{12,2}.(0.3)^{2}.(0.7)^{10} = 0.1678$

16.78% probability of making exactly two sales.

d. The mean number of sales in the two-hour period.

The mean of the binomia distribution is

$E(X) = np$

So

$E(X) = 12*0.3 = 3.6$

The mean number of sales in the two-hour period is 3.6.

4 0

3 years ago

Kevin and Randy Muise have a jar containing 70 coins, all of which are either quarters or nickels. The total value of the coins

Nikitich [7]

Answer:

50 nickels, 20 quarters.

Step-by-step explanation:

System of equations (q = # of quarters, n = # of nickels):

q + n = 70, 0.25q + 0.05n = 7.50

the first equation can be changed to q = 70 - n, so we are able to substitute q with 70 - n.

So, it will look like 0.25*70 - 0.25n + 0.05n = 7.50. This can be simplified to 0.2n = 10, which means that n = 50.

Knowing that we can solve q + 50 = 70, which means that q = 20.

6 0

3 years ago

Use the Parabola tool to graph the quadratic function. f(x)=2x^2−12x+19 Graph the parabola by first plotting its vertex and then

Debora [2.8K]

To find the vertex of our parabola, we are going to use the vertex formula: For a quadratic of the form $f(x)=x^2+bx+c$ it vertex $(h,k)$ is given by $h= \frac{-b}{2a}$ , $k=f(h)$ .
We can infet from our parabola that $a=2$ and $b=-12$ . So lets replace those values in our formula:
$h= \frac{-b}{2a}$
$h= \frac{-(-12)}{2(2)}$
$h= \frac{12}{4}$
$h=3$
$k=f(h)=2(3)^2-12(3)+19$
$k=2(9)-36+19$
$k=18-17$
$k=1$
The vertex $(h,k)$ of our parabola is $(3,1)$

Now to find our second point, we are going to evaluate our parabola at $x=0$
$f(0)=2(0)^2-12(0)+19$
$f(0)=0+0+19$
$f(0)=19$
Our second point is $(0,19)$

We can conclude that we can graph the parabola $f(x)=2x^2-12x+19$ using its vertex $(3,1)$ and the point $(0,19)$ as follows: