1) class mark of a particular class is 6 5 and class size is 3 , then class interval - Maths - Statistics

Question

1) class mark of a particular class is 6 5 and class size is 3 ,
then class interval is -
a) 5 - 8 b) 6 5 - 9 5 c) 3 5 - 6 5 d) none of these
2) the mean of 100 observations is 50 if the observation 50 is
replaced by 150 , what will be the resulting mean?

Harleen Birdi · Accepted Answer

@Suswagata: Here is the answer to your query (1) Class mark = 6 5 Class size = 3 If the class interval is aâ€“ b, then class mark $= \frac{a + b}{2}$ and class size = b â€“ a Here, $\frac{a + b}{2} = 6 5 and b - a = 3$ â‡’ a + b = 13 and a â€“ b = â€“ 3 On solving above two equations, we get a = 5 and b = 8 Thus, class interval is 5 â€“ 8 OR Lower limit of class interval = Class mark $- \frac{Class size}{2}$ $= 6 5 - \frac{3}{2} = 6 5 - 1 5 = 5$ Upper limit of class interval = Class mark + $\frac{Class size}{2}$ $= 6 5 + \frac{3}{2} = 6 5 + 1 5 = 8$ Thus, class interval is 5 â€“ 8 (2) Mean of 100 observations = 50 $\Rightarrow \frac{Sum of 100 observations}{100} = 50 (Mean = \frac{Sum of observations}{Number of observation})$ â‡’ Sum of 100 observations = 5000 On replacing 50 by 150, sum of observations will become 5000 â€“ 50 + 150 = 5100 $∴ New mean = \frac{5100}{100} = 51$ Hence, the new mean is 51

1) class mark of a particular class is 6.5 and class size is 3 , then class interval is - a) 5 - 8 b) 6.5 - 9.5 c) 3.5 - 6.5 d) none of these 2) the mean of 100 observations is 50 . if the observation 50 is replaced by 150 , what will be the resulting mean?

1) class mark of a particular class is 6.5 and class size is 3 , then class interval is -

a) 5 - 8 b) 6.5 - 9.5 c) 3.5 - 6.5 d) none of these

2) the mean of 100 observations is 50 . if the observation 50 is replaced by 150 , what will be the resulting mean?