Photoelectric Effect and stopping potential

Homework Statement

When 445 nm light strikes a certain metal surface, the stopping potential is 70% of that which results when 410 nm light strikes the same metal.

The Attempt at a Solution

$$P=0.7P'\\ \frac { nE }{ t } =\frac { 0.7nE' }{ t } \\ \frac { hc }{ λ } =\frac { 0.7hc }{ λ' } \\ \frac { λ' }{ λ } =0.7$$

And the question is???
Oh and you are neglecting the work function of the metal- I think

Opps. I didn't realize the question was cut off.

Here's the second part:

Based on this information and the table given in the textbook, identify the metal.

Basically, what is required is to calculate the work function.

A: work function 2.23 eV. Potassium.

bump

Show your effort please. As suggested, did you take the work function into account? Retry the problem.