Given set of scores= 62, 76, 42, 84, 21, 47, 28

We know the formula,

 $\mathrm{Average} \left(\mathrm{A}\right)=\frac{\mathrm{Sum} \mathrm{of} \mathrm{given} \mathrm{values} \left(\mathrm{S}\right)}{\mathrm{Total} \mathrm{number} \mathrm{of} \mathrm{values} \left(\mathrm{N}\right)}$

 Here,

 Sum of given values(S)

= 62+76+42+84+21+47+28

= 360

Total number of values(N)= 7

Substituting these values we get (A),

 $= \frac{360}{7}=51.42$

Hence, Option B is correct.