Question

If Mean = 53

Find 'R'​

Answer 1

C.I :- fi :- Xi :- fiXi :-

0-20. 12. 10. 120

20-40. 15. 30. 450

40-60. 22. 50. 1100

60-80. R. 70. 70R

80-100. 13. 90. 1170

sigma fi = 62 + R ; sigma fixi = 2840 + 70R

we know that,

$mean = \frac{sigma \: fixi}{sigma \: fi}$

But according to problem , mean is 53

So, by substituting we get

$53 = \frac{2840 + 70</strong><strong>R</strong><strong>}{62 + </strong><strong>R</strong><strong>}$

By cross multiplication, we get

$53(62 + </strong><strong>R</strong><strong>) = 2840 + 70</strong><strong>R</strong><strong>$

$3286 + 53</strong><strong>R</strong><strong> = 2840 + 70</strong><strong>R</strong><strong>$

$3286 - 2840 = 70</strong><strong>R</strong><strong> - 53</strong><strong>R</strong><strong>$

$446 = 17</strong><strong>R</strong><strong>$

$</strong><strong>R</strong><strong> = \frac{446}{17}$

$</strong><strong>R</strong><strong> = 26(approx.)$

• I hope it helps you.....✌️✌️