Question

Answer question no3 by direct mean formula

Answer 1

formula of mean is fixi/fi i.e upper class limit/lower class limit/2          ----------- (i)

Addition of 7 + 6 + 9 + 13 + f + 5 + 6  = 44 + f             ----- (ii)

11-13 xi = 11 +13 /2 = 12, fixi = 12 * 7 = 84
13-15, xi = 14, fixi = 84
15-17, xi = 16, fixi = 144
17-19, xi = 18, fixi = 234
19-21, xi = 20, fixi = 20f
21-23,xi = 22, fixi = 110
23-29, xi = 24, fixi = 96
                       --------------
                        752 + 20f                        ------------- (iii) 
                                            

Substitute (ii) and (iii) values in (i)

18 = 750 + 20f/44 + f

on cross multiplication we get

792 + 18f = 752 + 20f

f = 20.

Answer 2

$\huge\underline\bold\red{Given}$

Answer question 3 by direct mean formula

$\huge\underline\bold\pink{Answer}$

formula of mean is fixi/fi i.e upper class limit/lower class limit/2          ----------- (i)

Addition of 7 + 6 + 9 + 13 + f + 5 + 6  = 44 + f             ----- (ii)

11-13 xi = 11 +13 /2 = 12, fixi = 12 * 7 = 84

13-15, xi = 14, fixi = 84

15-17, xi = 16, fixi = 144

17-19, xi = 18, fixi = 234

19-21, xi = 20, fixi = 20f

21-23,xi = 22, fixi = 110

23-29, xi = 24, fixi = 96

                       --------------

                        752 + 20f                        ------------- (iii) 

                                            

Substitute (ii) and (iii) values in (i)

18 = 750 + 20f/44 + f

on cross multiplication we get

792 + 18f = 752 + 20f

f = 20.

$\huge\underline\bold\purple{ThankYou}$