The half-life of a radioactive substance is 27.7 years. a. Find the exponential decay model for this substance.
b. How long will it take a sample of 400 grams to decay to 300 grams?
c. How much of the sample of 400 grams will remain after 20 years?

N(t) = N₀·0.5^(t/27.7)

11.5 years

242.5 grams

Step-by-step explanation:

answer: are you

step-by-step explanation:

option 2 is correct.

step-by-step explanation:

we are given two inequality equation

x+y> 5 and -3x+2y< -2

first we draw the graph of both function using t-table method

equation: x+y> 5

for x=0, y=5

for x=-5, y=0

table:

x   :   0     5

y   :   5     0

test point (0,0) , 0> 5

false

equation: -3x+2y< -2

for x=0, y=-1

for x=2, y=4

table:

x   :   0     2

y   : -1       4

test point (0,0) , 0< -2

true

now we draw the graph. see the attachment for graph.

common region would be solution set.

option 2 is correct.