Analysis and Approaches for IBDP Maths Ebook 1 | Page 311

Front Page
(c) After ten years, there were 930 foxes in the reserve. Find k .
[3]
(d) During which year were the number of wolves the same as the number of foxes?
[4]
4. A health clinic counted the number of breaths per minute u and the number of pulse
beats per minute v for a patient t minutes after his 10 km race, as shown in the following
table.
Number of minutes ( t ) 1 3 5 6 7
Number of breaths per minute (u ) 58 55 53 50 52
The relationship between the variables is modelled by the regression line with equation
u �at � b .
(a) (i) Find the correlation coefficient.
(ii) Write down the exact value of a and of b .
[4]
(b) Use the regression line to estimate the number of breaths per minute 12 minutes
after the race, giving your answer to the nearest integer.
[3]
The number of pulse beats per minute v for the patient t minutes after his 10 km race
10
can be modelled by the equation v � � 70 , where
kt
k is a constant.
e
(c) After eight minutes, the number of pulse beats per minute is 75. Find k .
[3]
(d) After how many minutes do the number of pulse beats per minute 1.5 times the
number of breaths per minute?
[4]
22
www.seprodstore.com
303