Q14 of 141 Page 8

The arithmetic mean of the following data is 25, find the value of k.



















xi:



5



15



25



35



45



yi:



3



k



3



6



2



[CBSE 2001]






































X



y



yx



5



3



15



15



K



15k



25



3



75



35



6



210



45



2



90




N = 14 + k



∑yx = 15k + 390



Given,


Mean = 25


= 25


= 25


15k + 390 = 25 (14 + k)


15k + 390 = 350 + 25k


40 = 10k


k = 4


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12

Find the missing frequencies in the following frequency distribution if it is known that the mean of the distribution 50.

















x: 10



30



50



70



90



y: 17



f1



32



f2



19


 13

The arithmetic mean of the following data is 14. Find the value of k.



















xi:



5



10



15



20



25



yi:



7



k



8



4



5


 15

If the mean of the following data is 18.75. Find the value of p.



















xi:



10



15



p



25



30



yi:



5



10



7



8



2


 1

The number of telephone calls received at an exchange per interval for 250 successive one-minute intervals are given in the following frequency table.























No. of calls (x):



0



1



2



3



4



5



6



No. of intervals (f):



15



24



29



46



54



43



39



Compute the mean number of calls per interval.