Image formed by concave mirror; completed need someone to check

[hodgepodge]

Homework Statement

A person accidentally bit his tongue and wants to examine the bite by using a concave mirror. The mirror is placed 10 cm from the bite with the result that a virtual image of the bite appears 4 times actual size. Find the parameters s (distance from object to mirror), s' (distance from mirror to image), and R (radius of convex mirror).

Homework Equations

1/s + 1/s' = 1/f ; f=focal length
Magnification = -s'/s
f = R/2

The Attempt at a Solution

i got s = 10 cm
then using magnification formula (4 = -s'/s)
i got s' = -40 cm (negative b/c its a virtual image)
i then got focal length = 13.3333 using formula 1
so if f=R/2; R = 26.6667 cm

any input would be appreciated

 

[songoku]

Hi hodgepodge

I think you got it right

 

[rl.bhat]

Your solution is correct.

 

[hodgepodge]

thanks