No. of plants No. of houses (fi​) Mid point (Xi​) fi​xi​ 0−2  1  1   1 2−4  2  3  6 4−6  1  5  5 6−8  5  7  35 8−10  6  9  54 10−12  2  11  22 12−14  3  13  39 Total  20    162Calculating mean, we getMean, xˉ=n1​∑fi​xi​Here, n=20,∑fi​xi​=162Therefore, Mean, xˉ=20162​=8.1 plantsWe have used direct method because numerical values of f and x are small.