Question 14 Marks
Duration of sunshine(in hours) in Amritsar for first $10$ days of August $1997$ as reported by the Meterological Department are given as follows: $9.6, 5.2, 3.5, 1.5, 1.6, 2.4, 2.6, 8.4, 10.3, 10.9$
$i.$ Find the mean $\overline{\text{X}}$
$ii.$ Verify that $\sum\limits_{\text{i}=1}^{10}\Big(\text{X}-\overline{\text{X}}\Big)=0$
$i.$ Find the mean $\overline{\text{X}}$
$ii.$ Verify that $\sum\limits_{\text{i}=1}^{10}\Big(\text{X}-\overline{\text{X}}\Big)=0$
Answer
View full question & answer→Duration of sunshine $($in hours$)$ for $10$ days are $= 9.6, 5.2, 3.5, 1.5, 1.6, 2.4, 2.6, 8.4, 10.3, 10.9$
$i.$ Mean $X=\frac{\text{Sum of numbers}}{\text{Total numbers}}$
$=\frac{9.6+5.2+3.5+1.5+1.6+2.4+2.6+8.4+10.3+10.9}{10}$
$=\frac{56}{10}=5.6$
$ii. \text{L.H.S.}=\sum\limits_{\text{i}=1}^{10}\Big(\text{x}^\text{i}-\overline{\text{X}}\Big)$
$=\Big(\text{X}_1-\overline{\text{X}}\Big)+\Big(\text{X}_2-\overline{\text{X}}\Big)+\Big(\text{X}_3-\overline{\text{X}}\Big)+\dots+\Big(\text{X}_{10}-\overline{\text{X}}\Big)$
$= (9.6-5.6) + (5.2 - 5.6) + (3.5 - 5.6) + (1.5 - 5.6) + (1.6 - 5.6) \\+ (2.4 - 5.6) + (2.6 - 5.6) + (8.4 - 5.6) + (10.3 - 5.6) + (10.9 - 5.6)$
$= 4 - 0.4 - 2.1 - 4.1 - 4 - 3.2 - 3 + 2.8 + 4.7 + 5.3$
$= 16.8-16.8 = 0$
$i.$ Mean $X=\frac{\text{Sum of numbers}}{\text{Total numbers}}$
$=\frac{9.6+5.2+3.5+1.5+1.6+2.4+2.6+8.4+10.3+10.9}{10}$
$=\frac{56}{10}=5.6$
$ii. \text{L.H.S.}=\sum\limits_{\text{i}=1}^{10}\Big(\text{x}^\text{i}-\overline{\text{X}}\Big)$
$=\Big(\text{X}_1-\overline{\text{X}}\Big)+\Big(\text{X}_2-\overline{\text{X}}\Big)+\Big(\text{X}_3-\overline{\text{X}}\Big)+\dots+\Big(\text{X}_{10}-\overline{\text{X}}\Big)$
$= (9.6-5.6) + (5.2 - 5.6) + (3.5 - 5.6) + (1.5 - 5.6) + (1.6 - 5.6) \\+ (2.4 - 5.6) + (2.6 - 5.6) + (8.4 - 5.6) + (10.3 - 5.6) + (10.9 - 5.6)$
$= 4 - 0.4 - 2.1 - 4.1 - 4 - 3.2 - 3 + 2.8 + 4.7 + 5.3$
$= 16.8-16.8 = 0$