It is 300 miles per second
If you add the standard deviation to the average, it is 14.84. Because Marcus's score was lower than that, he will not receive a certificate.
I think this should be right for the reason and the calculation.
When you see the equals sign with a squiggly line on top, you know that the items on each side of the equation are congruent. Next, name the corresponding sides. Corresponding sides are matching sides between two triangles. They will have the same length in congruent triangles