Apps. and Interpretation for IBDP Maths Ebook 2 | Page 354

Your Practice Set – Applications and Interpretation for IBDP Mathematics
69.4
( a )
( i )
16.6
( ii )
3.3
( b )
n �
110
Chapter 17
Exercise 70
70.1 ( a ) 401g
( b )
sn
1 �
103 g
( c )
( 308.33 , 493.67 )
70.2 ( a ) 54 s ( b ) ( 43.442 , 64.558 )
70.3
( a )
n �
25
( b )
( 19.013 , 20.987 )
( c )
1.974
70.4
( a )
n �
16
( b )
( 68.685 , 71.315 )
( c ) 2.63
Exercise 71
71.1
( a )
20.65
( b )
� �
2.64
71.2
( a )
3.18
( b )
sn
1 �
0.448
71.3
( a )
A confidence interval with a smaller confidence level has a narrower interval about the mean .
( b )
( 36.4 , 38.6 )
( c )
sn
1 �
2.06
71.4
( a )
A confidence interval with a smaller confidence level has a narrower interval about the mean .
( b )
( 191.6 , 204.4 )
( c ) � � 7.45
Chapter 18
Exercise 72
72.1
( a )
( i )
a � 6226 , b �
2677
( ii )
30700 km
( b ) ( i ) r � 0.865
( ii )
2 R �
0.748
( iii )
74.8 % of the
variability of the data is explained by the regression model .
72.2
( a )
( i )
a �� 0.132 , b �
8.09
( ii )
4.79 g
( b ) ( i ) r �� 0.773
( ii )
2 R �
0.597
( iii )
59.7 % of the
variability of the data is explained by the regression model .
72.3
( a )
( i )
a � 0.533 , b �
13.9
( ii )
a represents the increase in expenditure when the time spent in a market increases by 1 minute .
( b )
( i )
r �
0.479
( ii )
2 R �
0.229
( iii )
22.9 % of the
variability of the data
is explained by the regression model .
72.4
( a )
( i )
a � 0.11, b ��
0.26
( ii )
b represents the annual corn yield rate when the annual rainfall is 0 cm .
( b )
( i )
r �
0.957
2
( ii ) R � 0.917
( iii ) 91.7 % of the variability of the data is explained by the regression model .
344
SE Production Limited