Question

Find the mean of each of the following frequency distributions:
class interval: 50-70 70-90 90-110 110-130 130-150 150-170
Frequency: 18 12 13 27 8 22

Answer 1

The Mean for the given Frequency Distribution is 112.2

Step-by-step explanation:

To find the mean for the given Frequency Distribution :

First to find x

$x=midpoint$

or $x=\frac{lower class interval+upper class interval}{2}$

• $x=\frac{50+70}{2}$
• $=\frac{120}{2}$

Therefore x=60

• $x=\frac{70+90}{2}$
• $=\frac{160}{2}$

Therefore x=80

• $x=\frac{90+110}{2}$
• $=\frac{200}{2}$

Therefore x=100

• $x=\frac{110+130}{2}$
• $=\frac{240}{2}$

Therefore x=120

• $x=\frac{130+150}{2}$
• $=\frac{280}{2}$

Therefore x=140

• $x=\frac{150+170}{2}$
• $=\frac{320}{2}$

Therefore x=160

Now we have the following table to find $\sum f$ and $\sum fx$ :

Class             f                x                fx

interval

_____________________________________

50-70           18             60             1080

70-90           12             80               960

90-110          13             100           1300

110-130         27            120           3240

130-150         8              140           1120

150-170         22            160           3520

______________________________________

                  $\sum f=100$                      $\sum fx=11220$

_______________________________________

Now $Mean=\overline{X}=\frac{\sum fx}{\sum f}$

• $\overline{X}=\frac{11220}{100}$
• $=112.2$

Therefore Mean=112.2

Answer 2

Answer:

hope this help you.........