Johnny was able to drive an average of 29 miles per hour faster on his car after the traffic cleared. He drove 30 miles in traff
1 answer:
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Answer: 20 mph
Explanation:
Speed is a physical quantity which is equal to the ratio between the distance covered (d) and the time taken (t):
In the first part of the problem, the plane flew a distance of d=400 mi in a time of t=2.5 h. The speed of the plane in this case was the difference between the proper speed of the plane, v, and the speed of the wind, w, since the plane flew opposite to the wind. So we can write:
(1)
During the return trip, the plane flew with a speed (v+w), since the wind was on the tail, and it took 2 hours to cover the same distance:
(2)
So we have two equations with two unknown variables. From (1), we get
Substituting into eq.(2)
So, the speed of the wind was 20 mph.
Answer:
a) The student's overall average for the class is 87.97.
b) He would need a score above 100 to get an A, which means that he could not have scored high enough on the final exam to get an A in the class.
Step-by-step explanation:
Weighed average:
To solve this question, we find the student's weighed average, multiplying each of his grade by his weights.
Grades and weights:
Scored 82.5 on the midterm, worth 30%.
Scored 88.6 on the final exam, worth 30%.
Scored 91.6 on the homework, worth 40%.
a. On a 100-point scale, what is the student's overall average for the class?
Multiplying each grade by it's weight:
The student's overall average for the class is 87.97.
b. The student was hoping to get an A in the class, which requires an overall score of 93.5 or higher. Could he have scored high enough on the final exam to get an A in the class?
Score of x on the final class, and verify that the average could be 93.5 or higher. So
He would need a score above 100 to get an A, which means that he could not have scored high enough on the final exam to get an A in the class.