a chart is an interaction graph obtained from a paper helicopter experiment with two factors Body length and Wing length, which affect the flying times of helicopters. Body length has two levels - 70 mm and 120 mm whereas Wing length has three levels - 70 mm, 120 mm, and 170 mm. Determine

• (a) the combination of Body and Wing lengths yielding the longest flying time
• (b) whether there is an interaction between Body and Wing lengths