The mean of the following frequency distribution is 25.2. Find the missing frequency x. Class
0 - 10
10 - 20
20 – 30
30 – 40
40 - 50

Frequency
8
x
10
11
9

Solution:-

Frequency Distribution     Frequency     Mid values     F*M

0 - 10                                    8                     5                40

10 - 20                                  x                    15               15x

20 - 30                                 10                   25               250

30 - 40                                 11                   35               385

40 - 50                                  9                    45               405

                                         Σf = 38+x                      Σfm = 1080+15x

Given Mean = 25.2

Mean = Σfm/Σf

25.2 = 1080+15x/38+x

25.2 × (38+x) = 1080+15x

957.6+25.2x = 1080+15x

25.2x - 15x = 1080 - 957.6

10.2x = 122.4

x = 122.4/10.2

x = 12

Missing frequency = 12  Answer

hello from mrbilldoesmath!

answer:

25x^2 + 90x + 84

discussion:

mn(x) = m(n(x)) = m( 5x + 9) =

(5x + 9)^2 + 3 =>

25x^2 + 90x + 9^2 + 3 =

25x^2 + 90x + 84                 (as 9^2 = 9*9 = 81)

which is the second choice

regards,  

mrb

p.s.   i'll be on vacation from friday, dec 22 to jan 2, 2019. have a great new year!

2 x 503

step-by-step explanation:

its 1006