Silvered slab problem: why is k positive when I got it negative?

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zorro
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Homework Statement



A point object is placed at distance of 40 cm from a composite refracting slab whose one face is silvered as shown. The separation between the object and its final image is (100 – k)cm. Find the value of k.

Ray diagram of a composite slab: point object O on the left in air (n = 1) 40 cm away; slab has a 9 cm section with n = 3/2 and a 10 cm section with n = 2, the right face silvered.



The Attempt at a Solution



I got the separation as 102cm. So k= -2
But the answer given is +2 and I am sure of my answer. Can somebody verify it?
 
Attachments
  • Diagram of a point object O on the left, 40 cm from a composite slab; left slab section n = 3/2 is 9 cm thick, right section n = 2 is 10 cm thick, with the right face silvered, and the surrounding medium n = 1.
    b4f1d478-29bc-4795-befe-f51493e8ecdc.jpg
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Discussion

I could see it. May be some problem. I reattached now.
 
Abdul Quadeer said:
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I got the separation as 102cm. So k= -2
But the answer given is +2 and I am sure of my answer. Can somebody verify it?

I got he same.

ehild