So close! But instead of adding the multiplication sign after the number you need to add them before. Good job though! :)
Answer:
1 1/4 hours
Step-by-step explanation:
.75/.6=x/1
cross multiply
.75=.6x
divide by .6
x=1.25 hours
Divide 150 by 50 to get 3
The answer is C. Circle
Hope this helps :)
Answer:
a)
, b)
, c)
, d) 
Step-by-step explanation:
a) Let assume an initial mass m decaying at a constant rate k throughout time, the differential equation is:

b) The general solution is found after separating variables and integrating each sides:

Where
is the time constant and 
c) The time constant is:


The particular solution of the differential equation is:

d) The amount of radium after 300 years is:
