Research scientists need a certain type of bacteria to conduct an experiment. There are 2,500 bacteria in a certain culture. The
culture grows at a rate of 25% daily. The scientists needs at least 10,000 bacteria to conduct an experiment. What is the least number of days they need to wait for the bacteria culture to reach a quantity of 10,000? (Hint: use a guess-and-check method to determine the lowest number of days that satisfy the requirement.)
1 answer:
Answer:
7 days
Step-by-step explanation:
At 25% per day, it will take approximately 3 days to double the population, so approximately 6 days for the population to quadruple. Checking that number, we find it is not quite enough for the experiment, so another day is required.
"Guess and check" as a method of solution works especially well if you have an automated checker to evaluate your guess. A graphing calculator or spreadsheet can work well for this.
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We guess 3 days as the doubling time using the "rule of 72" that says the product of percentage and doubling time is about 72. That is, 72/25 ≈ 3. (This is only a very rough approximation of doubling time, best for rates near 8%.)
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Answer:
(1) Area of second triangle= 50 cm^2.
(2) Area of ΔABC=98 cm^2.
and Area of ΔDFG=175 cm^2.
Step-by-step explanation:
<em>" For two similar triangles the ratio of sides is equal to the ratio of square of their areas".</em>
i.e. if a,b are the corresponding sides of two similar triangles and let A and B denote the area of two triangles then we have the relation as:
(1)
for the first question:
we have a=2, b=5.
A=8 cm^2.
Hence,
B=50 cm^2.
Hence, the area of second triangle is 50 cm^2.
(2)
In second option we have:
a=6 and b=5.
A-B=77 cm^2.
A=77+B
Hence area of second triangle i.e. ΔDFG is 175 cm^2.
and area of first triangle i.e. ΔABC=175-77=98 cm^2.
Answer:
r = 1 , 0
Step-by-step explanation:
-7 + 7r + 2 = 2
-7r(r-1)=2-2
-7r(r-1)=0
r-1=0
r=1