What is the maximum magnification achievable with a simple lens?

[floridianfisher]

Homework Statement

A boy scout starts a fire by using a lens from his eyeglasses to focus sunlight on kindling 5.2 cm from the lens. The boy scout has a near point of 15.2 cm. When the lens is used as a simple magnifier, give values for the following conditions. (Hint: Assume a "normal" eye.)
(a) What is the maximum magnification that can be achieved

(b) What is the magnification when the eye is relaxed

Homework Equations

1/p+1/q=1/f

Mmax= 1+ 25/q
Mrelaxed = 25/q

The Attempt at a Solution

I have tried 1/5.2 + 1/-(15.2-5.2) = 1/f
f=10.83
then I tried 1+ 25/10.83= 3.3 and 1+15.2/10.83=2.4 and both are wrong?
Please help

 

[chaoseverlasting]

You're using the mirror formula. You have to use the LENS formula. 1/v-1/u=1/f. Be careful about the signs of v and u. The direction of the ray of light is +ive and opposite is -ive.