Find the half-lives of the substances:

1) Einsteinium-253, which delays at a rate of 3.406% per day.

2) A radioactive substance that decays at a continuous rate of 11% at minute.

I don't know where to start. For the first one is the formula something like this? Q = Q0(1.03406)^t, solve for t. But whenever I solve it the answer comes out to be negative.

Also the second problem I don't know how to set up the equation. Does it involve e? Q = Q0(e^0.11)^t or Q = Q0(e^0.89)^t and solve for t?

Please help me with these problems. Thank you so much.