Answer
$μ=32.25$
$σ=5.7$
Work Step by Step
$x_1=$ First Class Midpoint = 17.5
$x_2=$ Second Class Midpoint = 22.5
$x_3=$ Third Class Midpoint = 27.5
$x_4=$ Fourth Class Midpoint = 32.5
$x_5=$ Fifth Class Midpoint = 37.5
$x_6=$ Sixth Class Midpoint = 42.5
$x_7=$ Seventh Class Midpoint = 47.5
$x_8=$ Eighth Class Midpoint = 52.5
$μ=\frac{Σx_if_i}{Σf_i}=\frac{17.5\times100+22.5\times467+27.5\times1620+32.5\times2262+37.5\times1545+42.5\times328+47.5\times85+52.5\times20}{6427}=32.3$
$σ=\sqrt {\frac{Σ(x_i-μ)^2f_i}{Σf_i}}=\sqrt {\frac{(17.5-32.25)^2\times100+(22.5-32.25)^2\times467+(27.5-32.25)^2\times1620+(32.5-32.25)^2\times2262+(37.5-32.25)^2\times1545+(42.5-32.25)^2\times328+(47.5-32.25)^2\times85+(52.5-32.25)^2\times20}{6427}}=5.7$
