Question

  

Recently, a random sample of13–18 year olds was​ asked, "How much do you currently have in​ savings?" The data in the table represent the responses to the survey. Approximate the mean and standard deviation amount of savings.

   0-199   0 199 348
200-399   200   399   90
400-599   400   599   52
600-799   600   799   25
800-999   800   999   10
1000-1199   1000   1199   7

1200-1399   1200   1399   2
      
The sample mean amount of savings is $

      
      
      
      

Answer 1

midpoint (X)	Frequency(f)	Freq*X	(X-mean)	(X-mean)2	f*(X-mean)2
99.5	348	34626	-133.333	17777.778	6186666.667
299.5	90	26955	66.667	4444.444	400000
499.5	52	25974	266.667	71111.111	3697777.778
699.5	25	17487.5	466.667	217777.778	5444444.444
899.5	10	8995	666.667	444444.444	4444444.444
1099.5	7	7696.5	866.667	751111.111	5257777.778
1299.5	2	2599	1066.667	1137777.778	2275555.556
Total ->	534	124333	-	-	27706666.66