Question

PLEASE SOLVE THE 3 QUESTION. IT IS VERY VERY IMPORTANT.​

Answer 1

$\displaystyle\sum_{i=1}^{m}(x_i-20)=15\\\\\\\sum_{i=1}^{m}x_i-\sum_{i=1}^{m}20=15\\\\\\\sum_{i=1}^{m}x_i-(m-1+1)20=15\\\\\\\sum_{i=1}^{m}x_i=20m+15\\\\\\\dfrac {1}{m}\sum_{i=1}^{m}x_i=\dfrac {20m+15}{m}\\\\\\\boxed {\overline{x}=20+\dfrac {15}{m}}$