Ringelmann (1913) found that when people worked in an interacting group on an additive task, the group performance was:

Worst than the sum of individual performances.

Explanation:

Through his experiment in 1913, Ringlemann found out what is nowadays known as the Ringelmann effect, or social loafing. According to this effect, the productivity of individual people reduces as the size of a group increases. People put less effort in shared tasks when they are part of a larger group.

254.34

step-by-step explanation:

the formula for area of a circle is given by

a = pi * r^2

a = pi * 9^2

a = 81*pi

using 3.14 as an approximation for pi

a = 3.14*81

a = 254.34

d. china

good luck

d is the best choice