Mutual Inductance

Two coils are wrapped around the same cylinder form. When the current in the first coil is decreasing at a rate of -.242A/s, the induced emf in the second coil has a magnitude of .00165 Volts. What is the mutual inductance?

What I did:

$$E_2 = -M(\frac{d_i_1}{d_t})$$

.00165/-.242 = -M

.006818H.

The answer given is 1.96H. I went over it several times and I keep coming back to this equation. Am I wrong, or is the book wrong?
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 I assume the book's wrong, your working looks fine to me.