The average annual return over the period 1926-2009 for the s& p 500 is 12.8%, and the standard
deviation of returns is 21.4%. based on these numbers, what is a 67% confidence interval for
2010 returns?
a) -1.3%, 20.5%
b) -8.6%, 34.2%
c) -25.8%, 54.7%
d) -25.8%, 47.9%

Answer: d. 39 cmin the diagram, the approximate length of the minor arc de is 39 centimetres.step-by-step explanation: the formula for the length of an arc in a circle is as displayed below.let the length of the minor arc de = xx = 2( pi )r × angle of sector / 360°from this, we will substitute the values given from the problem into the formula to obtain the length of the minor arc de.x = 2( pi )r × angle of sector / 360°r = radius = 25cmpi as an approximate value = 3.14angle of sector = 120°x = 2( 3.14 )( 25 ) × 120° / 360°x = 157 × 1 / 4x = 39.25x = 39 ( rounded to the nearest whole number as an approximate value )