Paper 1 – Coefficient of Determination

Example

The evaporation rates of six different chemical solutions are studied . Six different chemical solutions are stored in six different beakers . The storage time x ( in days ) and the corresponding loss in evaporation y ( in mL ) are shown in the following table .

Storage time ( x days ) 5 7 9 12 13 13 Loss in evaporation ( y mL ) 8 8 7 11 21 18

( a ) The relationship between the variables is modelled by the regression equation y �ax � b .

( i ) Write down the value of a and of b .

( ii ) Hence , estimate the loss in evaporation of a solution when it is stored for 10 days .

[ 4 ]

( b ) ( i ) Write down the correlation coefficient .

( ii ) Write down the coefficient of determination .

( iii ) Hence , interpret the coefficient of determination . [ 3 ]

( ii ) The estimated loss �1.410557185 ( 10 ) � 1.703812317 ( A1 ) for substitution � 12.40175953 mL � 12.4 mL

A1

[ 4 ] www . seprodstore . com

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