An energy drink company claims that its product increases students' memory levels. to support its claims, the company issues advertisements claiming that 8 out of 10 people (chosen randomly from across the country) who tried their product reported improved memory. the missing component in this study is a .

Control group

Step-by-step explanation:

A control group is necessary in all experiments that require a comparison. A control group and an experimental group are both included in an experiment. These two need to be identical in every way with the exception of the fact that the experimental group will be subjected to a treatment that is believed to have a particular outcome. In this case, it is difficult to know whether the drink really has the desired effects or not, as we are not aware of the results of a control group.

34.5 cm

step-by-step explanation:

generally for a circular segment of angle, θ° and radius r

arc length

= (θ/360) x circumference

= (θ/360) x 2πr

in our case, θ = 60°, π=3.142 and r = 33 cm

substitute into above formula

arc length

= (60/360) x 2(3.142)( 33) = 34.5 cm