Class intervalClass Marks \\\\((x_i)\\\\)Frequency \\\\((f_i)\\\\)Deviation \\\\((d_i=x_i-a)\\\\)\\\\(f_id_i\\\\) 100-104 102 15 -8 -120 104-108 106 20 -4 -80 108-112 110 32 0 0 112-116 114 18 4 72 116-120 118 15 8 120 \\\\(N=\\sum f_i=100\\\\) \\\\(\\sum f_id_i=-8\\\\)\\\\(\ herefore\\\\) Assumed mean, \\\\(a=110\\\\)Class width \\\\(h=4\\\\)and total observation, \\\\(N=100\\\\)Hence, finding mean\\\\(Mean(\\bar{x})=a+\\dfrac{\\sum f_1d_1}{\\sum f_1}\\\\)\\\\(=110+(-8/100)\\\\)\\\\(=110-0.08\\\\)\\\\(=109.92\\\\)But we know that the seats cannot be in decimalTherefore, the no, of seats \\\\(=109\\\\).