Michael needs to score an 86 on the final math test.
David needs to drive at an average speed of 75 mph.
The value of the second-largest number is 14.
Beth will arrive at Sam's house around 9:20 pm.
For the first question, to find the score Michael needs on his final math test to achieve a 90 average, we can set up an equation. The average of all six tests should be 90, so (95 + 87 + 85 + 93 + 94 + x) / 6 = 90, where x is the score on the final test. Solving this equation gives x = 86. This means Michael needs to score an 86 on the final math test to achieve a 90 average.
For the second question, the average speed is calculated by dividing the total distance by the total time. In this case, David needs to travel 450 miles in 6 hours, so his average speed would be 450 miles / 6 hours = 75 miles per hour.
Regarding the third question, let's represent the three consecutive even numbers as n, n+2, and n+4. The sum of the smallest and largest is given as 28, so n + (n+4) = 28. Solving this equation, we find n = 12. Therefore, the second-largest number is n + 2 = 14.
For the last question, if Beth is 500 miles away and travels at 60 mph, the time it takes to cover the distance is given by time = distance / speed. So, time = 500 miles / 60 mph, which is approximately 8.33 hours. If she leaves at 1 pm, she will arrive around 9:20 pm.