Acertain slide projector has a 100 mm focal length lens. how far away is the screen, if a slide is placed 103 mm from the lens and produces a sharp image?

3.43 m

Explanation:

f = 100 mm

u = - 103 mm

Let v be the distance between the screen and the lens of the projector.

Use lens equation

1 / f = 1 / v - 1 / u

1 / 100 = 1 / v + 1 / 103

1 / v = 1 / 100 - 1 / 103

1 / v = (103 - 100) / (100 x 103)

1 / v = 3 / 10300

v = 3433.33 mm = 3.43 m

i think its

if the person is shown to have +90n, then ans is -10n.

if the person is shown to have -90n, then ans is +10n.