Answer:
Explanation:
For Bill's glasses)
d_o=25 cm-2 cm=23.2 cm
d_i=129 cm-2 cm=127 cm
We know that
[tex]1 / f = 1 / d_o + 1 / d_i [/tex]
[tex]f=(1 / d_o + 1 / d_i)^-1 [/tex]
so plug the numbers in
[tex]f = (1 / (23) + 1 / (127))^-1 [/tex]
= 28.08 cm
For Anna's glasses)
d_o=25 cm-2 cm=23 cm
d_i=70.0 cm-2 cm=68 cm
Same thing
[tex](1 / f = 1 / d_o + 1 / d_i )[/tex]
[tex]f=(1 / do + 1 / di)^-1 [/tex]
so plug the numbers in
[tex]f = (1 / (23) + 1 / (68))^-1 [/tex]
= 17.21 cm