Question

The following table shows the number of saplings planted by 30 students. Fill in the boxes and find the average number of saplings planted by each student.

No. of saplings (Scores) xi	No. of students (frequncy) fi	fi×xi
1	4	4
2	6	$\boxed{0}$
3	12	$\boxed{0}$
4	8	$\boxed{0}$
	N = $\boxed{0}$	∑fixi=$\boxed{0}$

Mean $\overline{x}$ = $\frac{\boxed{0}}{N}$

= $\frac{\boxed{0}}{\boxed{0}}$

= $\boxed{0}$

∴ The average number of trees planted $\boxed{0}$

Answer 1

No. of saplings (Scores) xi	No. of students (frequncy) fi	fi×xi
1	4	4
2	6	= 2 $\times$ 6 = $\boxed{12}$
3	12	= 3 $\times$ 12 = $\boxed{36}$
4	8	= 4 $\times$ 8 = $\boxed{32}$
	N = $\boxed{30}$	∑fixi=$\boxed{84}$

Mean $\overline{x}$ = $\frac{\boxed{{\displaystyle \sum _{}{f}_i{x}_x}}}{N}$

= $\frac{\boxed{84}}{\boxed{30}}$

= $\boxed{2.8}$

∴ The average number of trees planted $\boxed{2.8}$