Question

The mean of the following frequency table is 50. But the frequencies J, and f, in classes
20- 40 and 60 - 80 are missing. Find the missing frequencies.
correct mean.
8
Class
0-20
20-40
40 - 60
60 - 80
80 - 100
Frequency
19
j
32
f
19
(total 120)​

Answer 1

Step-by-step explanation:

You have to use mean Formula.

Answer 2

Answer:

Step-by-step explanation:

17+32+9+f1+f2=120

=>f1+f2=52 -------(¡)

[(summation)fixi]/[(summation)fi]=50 [GIVEN]

=>[3480+30f1+70f2]/120=50

=>30f1+70f2=(50×120)-3480=2520

=>10 (3f1+7f2)=2520

=>3f1+7f2=252 ---------(ii)

so, now we subtract [equation(i)×3] and [equation(ii)],we get:-

equation(i)×3--- 3f1+3f2= 156

equation (ii)----- +3f1+7f2=+252

(-) (-) (-)

_____________

0-4f2=-96

=>f2=24

Putting the value of f2=24 in equation (i), we get :-

f1+24=52

=>f1=52-24=28

So, f1=28 and f2=24