Average height (in cm) of the girls whose heights are 155 cm and above is about-

Answer: Option B

Take value of class interval 155 - 160 and 160 - 165 i.e. 157.5 and 162.5.
Multiply them by their respective frequency and then divide by total no. of girls.
$$\begin{array}{rl}& =\frac{157.5\times 6+162.5\times 5}{11}\\ & =\frac{945+812.5}{11}\\ & =\frac{1757.5}{11}\\ & =159.8\text{ cm}\end{array}$$