AP ICET 2019 Shift 2 Paper

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Question : 141 of 200

Marks: +1, -0

If the mean of the following distribution is 50. then the ratio of the missing frequencies

f_1

and

f_2

is

C.I	0-20	20-40	40-60	60-80	80-100	Total
$f_i$	17	$f_1$	32	$f_2$	19	120

6 : 5
7 : 5
7 : 6
8 : 5

Solution:

C.I	$f_i$	$x_i$	$f_ix_i$
0 – 20	17	10	170
20 – 40	$f_1$	30	$30f_1$
40 – 60	32	50	1600
60 – 80	$f_2$	$70$	$70f_2$
80 – 100	19	90	1710
	$68+f_1+f_2$		$3480 + 30f_1 + 70f_2$

68+f 1+f 2=120 ⇒ f_{1}+f_{2}=52

→ (1)

\;{3480+30 f 1+70 f 2}/{120}=50 ⇒ 3 f_{1}+7 f_{2}=252

→ (2)

Solving (1) & (2)

f_1=28,f_2=24

f_1:f_2=7:6

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