9514 1404 393
Answer:
Step-by-step explanation:
The decay factor is 1 -25% = 0.75 per hour, so the exponential equation can be written ...
r(t) = 1450·0.75^t . . . . . milligrams remaining after t hours
__
a) After 4 hours, the amount remaining is ...
r(4) = 1450·0.75^4 ≈ 458.79 . . . mg
About 459 mg will remain after 4 hours.
__
b) To find the time it takes before the amount remaining is less than 5 mg, we need to solve ...
r(t) < 5
1450·0.75^t < 5 . . . . use the function definition
0.75^t < 5/1450 . . . . divide by 1450
t·log(0.75) < log(1/290) . . . . . take logarithms (reduce fraction)
t > log(1/290)/log(0.75) . . . . . divide by the (negative) coefficient of t
t > 19.708
It will take about 20 hours for the amount of the drug remaining to be less than 5 mg.
If you are talking about the area and perimeter of one of the triangular faces...
8 x 1.2 = 9.6
6 x 1.2 = 7.2
Perimeter = 9.6 + 7.2 + 7.2 = 24
Area = Linear Scale Factor²
1.2² = 1.44
7 x 1.44 = 10.08 (units)²
It will take Fred 42 minutes to type and spell check 60 pages.
- Let the first scenario be A.
- Let the second scenario be B.
- Let the unknown time be X.
Given the following data;
- Number of pages A = 13 pages
- Number of pages B = 60 pages
To find how long it takes him to type and spell check 60 pages;
We would use direct proportion to express the work described and solve for the unknown variable (time).

Cross-multiplying, we have;
×
× 

<em>X = 41.54 ≈ 42 minutes</em>
Therefore, it will take Fred 42 minutes to type and spell check 60 pages.
Find more information: brainly.com/question/89674