Answer
$μ=29.9$
$σ=20.3$
Work Step by Step
$x_1=$ First Class Midpoint = 9
$x_2=$ Second Class Midpoint = 21.5
$x_3=$ Third Class Midpoint = 30
$x_4=$ Fourth Class Midpoint = 40
$x_5=$ Fifth Class Midpoint = 50
$x_6=$ Sixth Class Midpoint = 57.5
$x_7=$ Seventh Class Midpoint = 62.5
$x_8=$ Eigth Class Midpoint = 70
$μ=\frac{Σx_if_i}{Σf_i}=\frac{9\times15451+21.5\times6071+30\times6123+40\times4756+50\times4421+57.5\times1792+62.5\times1520+70\times3433}{43567}=29.9$
$σ=\sqrt {\frac{Σ(x_i-μ)^2f_i}{Σf_i}}=\sqrt {\frac{(9-29.9)^2\times15451+(21.5-29.9)^2\times6071+(30-29.9)^2\times6123+(40-29.9)^2\times4756+(50-29.9)^2\times4421+(57.5-29.9)^2\times1792+(62.5-29.9)^2\times1520+(70-29.9)^2\times3433}{43567}}=20.3$
