Here,17+19+32+f1+f2=120 ⇒f1+f2=52......(i) ∵ mean
∑fixi
∑fi
⇒
3480+30f1+70f2
120
=50 ⇒3f1+7f2=252.....(ii) from (i) and (ii), we have: 3f1+7f2=252 3f1+3f2=156 −‌‌‌−‌‌‌‌‌− ––––––––––––– ⇒f2=24 ⇒f1=52−f2=52−24=28