Q9 of 79 Page 24

Find the mean of the following distribution.



















x:



10



12



20



25



35



f :



3



10



15



7



5







































x



f



fx



10



3



30



12



10



120



20



15



300



25



7



175



35



5



175




N = 40



∑fx = 800



Therefore, mean () =


=


= 20


Therefore, = 20


More from this chapter

All 79 →
7

Find the missing frequency (p) for the following distribution whose mean is 7.68.





















x:



3



5



7



9



11



13



f :



6



8



15



p



8



4


 8

Find the value of p, if the mean of the following distribution is 20.



















x:



15



17



19



20+p



23



f :



2



3



4



5p



6


 10

Candidates of four schools appear in a mathematics test. The data were as follows:













Schools



No. of Candidates



Average Score



I


II


III


IV



60


48


Not available


40



75


80


55


50



If the average score of the candidates of all the four school is 66, find the number of candidates that appeared from school III.

 11

Five coins were simultaneously tossed 1000 times and at each toss the number of heads were observed. The number of tosses during which 0, 1, 2, 3, 4 and 5 heads were obtained are shown in the table below. Find the mean number of heads per toss.















No. of heads per toss



No. of tosses



0


1


2


3


4


5



38


144


342


287


164


25



Total



1000