165
∑fx = (160 * 4) + (161 * 6) + (162 * 3) + (163 * 7) + (164 * 8) + (165 * 9)
=640 + 966 + 486 + 1,141 + 1,312 + 1,485
= 6,030
∑f = 4 + 6 + 3 + 7 + 8 + 9
= 37
= ∑fx∑f
= 603037
= 162.97 or 163