A rectangular piece of gold is 3.6 cm long and 3.5 cm wide. How deep is the piece when it displays a resistance of R = 1.51 ìù for a current that flows along the depth-direction?

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p is found in a table...right?
and then..
R=pl/A
R=pl/(2dw+2wl+2dl)
then solve for d...
i did this but got the answer wrong..where am i making mistakes???

Your area A is wrong. It should be

A = 3.5 cm * w,
the cross sectional area through which the current flows. You wrote the surface area of the bar.