Question

The table shows the daily sales (in $1000) of shopping mall for some randomly selected days Sales 1.1-1.5 1.6-2.0 2.1-2.5 2.6-3.0 3.1-3.5 3.6-4.0 4.1-4.5 Days 18 27 31 40 56 55 23 Use it to answer questions 13 and 14. 13. What is the approximate value for the modal daily sales? A. $3,129.41 B. $2,629.41 C. $3,079.41 14. The approximate median daily sales is ... A. $3,130.36 B. $2,680.36 C. $3,180.36 D. $3,123.53 D. $2,664.29

Answer 1

Answer:

Step-by-step explanation:

From the question; we are given the following inclusive frequency distribution information

Class                Frequency f

1.1-1.5                           18

1.6-2.0                         27

2.1-2.5                         31

2.6-3.0                        40

3.1-3.5                         56

3.6-4.0                        55

4.1-4.5                          23

Convert the above inclusive frequency distribution to exclusive frequency distribution with respect of the upper and lower class limit ; we have:

Class                             Frequency f

1.05 - 1.55                             18

1.55 - 2.05                           27

2.05 - 2.55                          31

2.55 - 3.05                          40

3.05 - 3.55                          56

3.55 - 4.05                          55

4.05 - 4.55                          23

Class                             Frequency f                     cf

1.05 - 1.55                             18                              18            

1.55 - 2.05                           27                               45

2.05 - 2.55                          31                               76

2.55 - 3.05                          40                               116

3.05 - 3.55                          56                               172

3.55 - 4.05                          55                               227

4.05 - 4.55                          23                               250

                                       n = 250

To determine the daily sales; we can derive that from estimated Mode by using the relation :

Estimated Mode = L + fm − fm-1(fm − fm-1) + (fm − fm+1) × w

here:

L  = the lower class boundary of the modal group

fm-1 =  the frequency of the group before the modal group

fm = the frequency of the modal group

fm+1 = the frequency of the group after the modal group

w  = the group width

However;

It is easier now to determine  the modal group (i.e the group with the highest frequency), which is 3.05 -3.55

L = 3.05

fm-1 =40

fm =56

fm+1 = 55

w = 0.5

∴$mode = 3.05 + \dfrac{56 - 40 }{(56 - 40) + (56 -55)} * 0.5 \\ \\ mode = 3.05 + 0.4705 \\ \\ mode = 3.5205$

To find Median Class ; we use the formula;

Median Class = value of (n / 2)th observation

Median Class  = value of (250 / 2)th observation  

Median Class = value of 125th observation

From the column of cumulative frequency cf,

we will see that the 125th observation lies in the class 3.05-3.55.

∴ The median class is 3.05-3.55.

Thus;,  

L=lower boundary point of median class =3.05

n=Total frequency =250

cf=Cumulative frequency of the class preceding the median class =116

f=Frequency of the median class =56

c=class length of median class =0.5

$Median M=L+n2-cff- c \\ \\ =3.05+125-11656⋅0.5 \\ \\=3.05+0.08036 \\ \\ =3.13036$

hence median sales = $3130.36