The half life of a certain substance is about 4 hours. the graph shows the decay of a 50 gram sample of the substance that is measured every hour for 9 hours.

a graph shows time (hours) labeled 1 to 10 on the horizontal axis and quantity (grams) on the vertical axis. a line decreases from 0 to 9.

which function can be used to determine the approximate number of grams of the sample remaining after t hours?

y = 25(0.15)t
y = 25(0.85)t
y = 50(0.15)t
y = 50(0.85)t

Step-by-step explanation:

Let the equation that models the decay of the substance is given by  

........... (1)

where y is the amount of the substance remaining after t hours and represents the initial amount of the substance and k is the decay rate constant.

Now, given that the half-life period of the substance is 4 hours.

So, from equation (1) we can write

Now, taking ln on both sides we get

ln 0.5 = -4k

⇒ k = 0.17328

Therefore, the equation (1) becomes  

{Since the initial amount of the substance was 50 gm}

⇒ (Approximate) (Answer)

D

Step-by-step explanation:

50(.85)^t

step-by-step explanation: i dont

the answer is ! ?