Answer:
I believe that it is the first one.
Step-by-step explanation:
3a) Answer: 84 degrees
Step-by-step explanation:
3x + 2(x+20)= 180 (total sum of angles in a triangle is 180 degrees)
5x+40 = 180
5x = 140
x= 28
3x= 28 x 3
= 84
To find out if a triangle is a right triangle, you can use the Pythagorean theorem(which can only be used for right triangles):
a² + b² = c² (c is the hypotenuse or the longest side) And you can plug in the side lengths into this equation. If they are the same number on both sides, it is a right triangle, if they are different numbers it is not a right triangle.
6.) a² + b² = c²
(4√3)² + (11)² = (13)²
(16(3)) + 121 = 169
48 + 121 = 169
169 = 169 It IS a right triangle
7.) a² + b² = c²
(5)² + (2√14)² = (9)²
25 + (4(14)) = 81
25 + 56 = 81
81 = 81 It IS a right triangle
8.) a² + b² = c²
(6)² + (√49)² = (√82)²
36 + 49 = 82
85 = 82 It is NOT a right triangle
9.) a² + b² = c²
(13)² + (2√39)² = (16)²
169 + (4(39)) = 256
169 + 156 = 256
325 = 256 It is NOT a right triangle
Answer:
The approximate percentage of SAT scores that are less than 865 is 16%.
Step-by-step explanation:
The Empirical Rule states that, for a normally distributed random variable:
Approximately 68% of the measures are within 1 standard deviation of the mean.
Approximately 95% of the measures are within 2 standard deviations of the mean.
Approximately 99.7% of the measures are within 3 standard deviations of the mean.
In this problem, we have that:
Mean of 1060, standard deviation of 195.
Empirical Rule to estimate the approximate percentage of SAT scores that are less than 865.
865 = 1060 - 195
So 865 is one standard deviation below the mean.
Approximately 68% of the measures are within 1 standard deviation of the mean, so approximately 100 - 68 = 32% are more than 1 standard deviation from the mean. The normal distribution is symmetric, which means that approximately 32/2 = 16% are more than 1 standard deviation below the mean and approximately 16% are more than 1 standard deviation above the mean. So
The approximate percentage of SAT scores that are less than 865 is 16%.
