Explanation

Let the radius be r, so the diameter is 2r and the circumference is 2πr. The condition 'circumference exceeds the diameter by 16.8 cm' gives 2πr − 2r = 16.8, i.e. 2r(π − 1) = 16.8. With π = 22/7, π − 1 = 15/7, so 2r × 15/7 = 16.8 and 2r = 16.8 × 7/15 = 117.6/15 = 7.84 cm. Hence option (d). The distractors come from arithmetic slips in the fraction 16.8 × 7/15 or from using 2π instead of 2(π − 1).