95% of a radioactive material remains after 25 days.

Part 1: Find the decay constant. IMPORTANT: Decimal answers will be marked incorrect--a decimal point can't be ANYWHERE in your answer. Enter an EXACT, symbolic answer (such as 3/2, not 1.5, or ln(2), not 0.69)

Decay constant=

Part 2: Find the time T (in days) after the initial measurement when 40% of the original amount of radioactive material remains. You may enter a symbolic answer or round your answer to the nearest whole number.

WARNING: Do not round off values during intermediate calculations, as error may compound to give you an inaccurate answer.

T=