SAMPLING NORMAL POPULATIONS 



Ch. 6 



162 



observations. The t's were computed from formula 6.34, using n = 60 

 and the al's obtained from the samples. For example, if the x = 58.2 

 and s £ is calculated from formula 6.33 to be 2.61, t = (58.2 - 60)/2.61 

 = -0.69. 



TABLE 6.31 



Observed Frequency Distribution of 580 U Obtained from Samples of 

 10 Members Each Drawn from a Normal Population with ix = 60 and 



a = 10 



Figure 6.31 presents the frequency and the relative cumulative fre- 

 quency distribution curves corresponding to Table 6.31. The r.c.f. 



= 1.00 



-3.60-2.80-2.00-1.20-0.40 0.40 1.20 2.00 2.80 3.60 



t 



Figure 6.31. Frequency distribution of 580 sample values of t drawn 

 normal population with n = 60, <r = 10, and n = 10. 



from a 



curve of Figure 6.31 furnishes information concerning the population 

 of ti for n = 10 which is entirely analogous to that to be had from 

 Table III for normal frequency distributions. Figure 6.31 shows 

 that: (a) The point where t = on the horizontal axis divides the 

 population of t's into two equal portions, each containing 0.50, or 

 50 per cent, of the whole population (as with the normal distribution 



