Question

Hi I need help plotting this graph from my thin lenses lab. They want me to pick two sets of points from my data. The first set will become p1 and q1 and the second set will become p2 and q2. Plot q1 and p1, and q2 and p2 on the same graph. (Hint: select values of p1 and p2 such that the difference between them is at least 30cm.) I'm using this to find the the intersection of the two lines on the graph because that will be the focal length. When I tried it, my graph didn't intersect. Thank you!

Data:

Position of lens(cm):
61
34
66.5
33.2
77.9
32.0
78.6
31.1
84.4
30.1

Position of screen(cm):
90
90
95
95
100
100
105
105
110
110

Answer 1