The best approach to this is to use the formular
Standard error = standard deviation / sqrt( sample size)
standard deviation = 0.75 hours
sample size = 35
Hence, Standard error = 0.75 /sqrt(35) = 0.126 = 0.13
Your answer would be 2.6 meters per second
390 ÷ 150 = 2.6
Looks good to me. Calculation is correct. Although you might want to add to #1 your description; that the width of the rectangle is the circumference of the circle (w = 2πr) and that you add the surfaces together to get the total surface area.
total surface area = area of rectangular part + area of circular parts
SA = 2πrL + 2πr²
I’m assuming you mean -1/4 -4, and since you’re subtracting a negative by a negative, it would be -4 1/4(mixed number)
