Helena scored a 75 on a history exam and an 80 on a science test. The class average for the history test was 70 with a standard deviation of 2.5. The class average for
the science test was 75 with a standard deviation of 5. She believes that she did
better in science than history in comparison with her class. Explain her error

cross multiplying, we get :

⇒ (3) × (5) = (9) × (x)

⇒ 15 = 9x

arc length = 6.63311 ft.

step-by-step explanation:

the formula the arc measure is:

arc length s=2πr(c)/360

where:

c   is the central angle of the arc in degrees

r   is the radius of the arc

π   is pi, approximately 3.142

using the above formula we get

s =

thus we find that arc length of an arc for a circle of radius 20 feet and central angle 19 degrees is

6.63311 feet