In 2016, the mean score on the AP Art History exam was 3.8, with a standard deviation of 1.2. The mean score on the AP English exam was a 2.9, with a standard deviation of 1.7. What is the combined mean and standard deviation for these exams?

A.) Mean, 0.9; standard deviation, 0.2
B.) Mean, 3.35; standard deviation, 2.9
C.) Mean, 3.35; standard deviation, 1.45
D.) Mean, 6.7; standard deviation, 2.08
E.) Mean, 6.7; standard deviation, 4.33

The mean is given by:

And the standard deviation would be:

And the distribution for X+Y would be:

And the best answer would be:

D.) Mean, 6.7; standard deviation, 2.08

Step-by-step explanation:

Let X the random variable who represent the AP Art History exam we know that the distribution for X is given by:

Let Y the random variable who represent the AP English exam we know that the distribution for X is given by:

We want to find the distribution for X+Y. Assuming independence between the two distributions we have:

The mean is given by:

And the standard deviation would be:

And the distribution for X+Y would be:

And the best answer would be:

D.) Mean, 6.7; standard deviation, 2.08

a4 - 3a2 - 1

step-by-step explanation:

step   1   :

equation at the end of step   1   :

  ((a4) -   3a2) -   1

step   2   :

trying to factor by splitting the middle term

2.1     factoring   a4-3a2-1  

the first term is,   a4   its coefficient is   1 .

the middle term is,   -3a2   its coefficient is   -3 .

the last term, "the constant", is   -1  

step-by-step explanation:

the multiplicative inverse of a fraction a/b is b/a. for the multiplicative inverse of a real number, divide 1 by the number. for example, the reciprocal of 5 is one fifth 1/5 or 0.2, and the reciprocal of 0.25 is 1 divided by 0.25, or 4.