Pearl solved a system of equations using substitution. Did she do it correctly? How do you know? If she did not find her error and solve the system correctly. 2x + (-5 - x) = 20 r-5= 20 X-5 + 5 = 20 + 5 x= 25 System: y=-5-X 2x + y = 20 Pearl's Solution: r = 25 y = -30

Describe in detail how you would construct a 95% confidence interval for a set of 30 data points whose mean is 20 and population standard deviation is 3. be sure to show that you know the formula and how to plug into it. also, clearly state the margin of error.

3.17 scores on stats final. below are final exam scores of 20 introductory statistics students. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 57, 66, 69, 71, 72, 73, 74, 77, 78, 78, 79, 79, 81, 81, 82, 83, 83, 88, 89, 94 (a) the mean score is 77.7 points. with a standard deviation of 8.44 points. use this information to determine if the scores approximately follow the 68-95-99.7% rule. (b) do these data appear to follow a normal distribution? explain your reasoning using the graphs provided below.

Ntriangle abc, m∠a = 35° and m∠b = 40°, and a=9. which equation should you solve to find b?