Answer:
56.42 minutes
Step-by-step explanation:
The initial sample= y0 = 800
After 13 minutes , amount = 320
Y= y0e-kt
320 = 800e-k(13)
320/800 = e-k13
0.4 = e-k13
In0.4 = -k13
-0.91629= -k13
0.07048= k
Y = 800e-0.07048t
Minutes when the bacterial present will be 15
15 = 800e-0.07048t
15/800= e-0.07048t
0.01875 = e-0.07048t
In 0.01875 = -0.07048t
-3.97656 = -0.07048t
-3.97656/-0.07048= t
56.42 = t
56.42 minutes
Answer:13.86km
Step-by-step explanation: see attachment
Okay, take a look at diagram 1 (I know it's rubbish I did it on paint :D), this shows all the information you've given in the question. The two coordinates and the distance between them.
Now if we draw additional lines on this diagram, we can make a right-angled triangle (this is on diagram 2). We can also work out the lengths of the additional sides because we know both coordinates at the end-points of the additional lines.
Finally because this is a right-angled triangle, Pythagoras' theorem must apply to its sides meaning



therefore x=5.