Seniors at a local high school took both the ap statistics exam and the ap literature exam. on the statistics test, the mean score was 2.4 with a standard deviation of 0.6. on the literature test, the mean score was 2.65 with a standard deviation of 0.55. if we wanted to look at the combined scores (and assumed the tests were independent), what would their mean and standard deviation be?

5.05, 0.66
5.05, 1.15
5.05, 1.07
5.05, 0.82
5.05, 0.42

The answer is 5.05 and 0.82

As standard deviation is the square root of variance, so we take the square root of variance to get the new standard deviation.

Sum of means = 2.45+2.65 = 5.05
Combined mean = 5.05/2 = 2.525
variance = 0.36+0.3025 = 0.6625

combined standard deviation = square root (0.6625) = 0.814 ~ .82

Okay so for every triangle has three angles that always add up to 180 degrees. and to tell the difference between whether they are secure, right or obtuse is that acute: has one angle that is less than 90 degrees. right triangle means there is at least one angle that is exactly 90 degrees. and an obtuse angle has an angle that is bigger than 180 degrees. i’ll do #13 as an example: 13. 40 and 50 so if every triangle has 180 degrees 40+50= 90 degrees then180-90= 90 degrees so the third angle is 90 degrees and because this triangle has a 90 degree angle it means it is a right triangle