Your Practice Set – Applications and Interpretation for IBDP Mathematics
Part II – Models for the Population 2
The following table shows the number of books y , sold by Olga each year , where n is the number of years after 2000 :
n |
1 |
2 |
3 |
4 |
5 |
7 |
9 |
y |
390 |
386 |
381 |
375 |
368 |
349 |
330 |
( c ) The relationship between the variables is modelled by the regression equation n y( n) �a� b .
( 1 ) Write down the equation of the least square regression curve , giving the coefficients correct to 5 significant figures if necessary .
( 2 ) Write down the coefficient of determination .
( 3 ) Hence , interpret the coefficient of determination .
Olga would like to conduct a
2
� goodness of fit test at a 2.5 % significance level to determine if the actual number of books sold by her can be modelled by the following distribution :
n |
1 |
2 |
3 |
4 |
5 |
7 |
9 |
Expected frequency |
400 |
400 |
380 |
380 |
360 |
340 |
320 |
( d ) ( 1 ) Write down the degree of freedom of the test .
2
( 2 ) Find the value of � calc
, the test statistic .
The critical value is given by 14.449 .
( 3 ) State the conclusion of the test with a reason .
312
SE Production Limited