There are 2,100 bacteria in a circular petri dish. The dish has a radius of 40 millimeters. What is the approximate population density? (Use 3.14 for π)

Answers

Answer 1

Answer: A petri dish is simply a circle; thus, we use the formula of the area of the circle which is πr^2.
Given r = 40 mm
A = π(40)^2 = 5026.55 sq. mm

Population density = bacteria count / area
PD = 2,100 / 5026.55
PD = 0.417782 bacteria / mm sq.

Therefore, the answer is approximately 0.418 bacteria per square millimeter.

Answer 2

Answer: Determine the area of the circular petri dish through the equation, A = πr^2. Substituting the radius to the equation and solving for area gives, 5024 mm^2. The population density is obtained by dividing the population with the calculated area. Thus, the population density is approximately 0.418 bacteria per mm^2.

Related Questions

In a week, 12 hens laid 60 eggs. What is the unit rate for eggs per hen? The unit rate is ______ egg(s) per hen
Find the X-intercept of the line 4x+11y=20
A balloon has a circumference of 28 in. Use the circumference to approximate the volume of the balloon to the nearest square inch.Answer choices:3,659 in ^311,488 in ^32,964 in ^3944 in ^3
What is the value of any fraction with 0 in the denominator
What is the answer to this?

Jodi is retiring at the age of 65. When she retires, she estimates that she will need a monthly income for 25 years. If Jodi starts with $328,133.32 in an account that pays 6.2% interest compounded montly, approximately what monthly income will she be able to draw?

Answers

Given:
Principal = 328,133.32
Interest rate = 6.2%, compounded monthly
term = 25 years

A = P (1 + r/n)^nt
A = 328,133.32 (1 + 6.2%/12)^12*25
A = 328,133.32 (1 + 0.0052)^300
A = 328,133.32 (1.0052)^300
A = 328,133.32 (4.74)
A = 1,555,351.94 Total value after 25 years.

1,555,351.94 / 300 months = 5,184.51 per month.

Answer:The correct answer is B:2,154

Step-by-step explanation:

Show your working for the following questions:-18 divided by -3

Two sevenths times eight thirds

Three eights plus one twelth

Answers

$(-18)/(-3)$ (divide 3 from numerator and denominator) = $(6)/(1) = 6$

$(2)/(7)$ × $(8)/(3)$ = $(16)/(21)$

$(3)/(8) + (1)/(12) = (9)/(24) + (2)/(24) = (11)/(24)$

What is 90% of 81?
X

Answers

Answer:

72.9

Step-by-step explanation:

Fractions method:

$81*(90)/(100)$ because 90/100 is the same thing as 90%

That gives us 7290/100, from 81*90/100

Simplify: =729/10 = 72.9

Decimals method:

81*9 = 729, add in decimal and that's 72.9

Cross-multiplication:

90 100

? 81

This is read as 90 to 100, (as a ratio) so how many to 81? To solve, cross-multiply - 81*90=7290, then divide by 100 to get 72.9.

This is my first answer , hope it helped!

Answer:72.9

Step-by-step explanation:

Find the surface area of the prism

Answers

surface area of one face = 9x9 = 81
total no. of faces = 6
total surface area of prism = 81 x 6 = 486in.

The length of a photograph is 3cm less than twice the width. the area is 54cm. whats the demention

Answers

Knowing that 6*9=54, and using the formula:
L=2w-3
2(6)-3
12-3
9=L

Use the discriminant to determine the number of solutions of the quadratic equation, and whether the solutions are real or complex. Note: It is not necessary to find the roots; just determine the number and types of solutions.2x^2 + x - 1 = 0
4/3x^2 - 2x + 3/4 = 0

Answers

Discriminant is b²-4ac in a quadratic equation Ax²+ Bx+C=0.

If the value of discriminant is less than zero, then the equation has two complex solutions
If the value of the discriminant is equal to zero, then the equation has one solution
If the value of the discriminant is more than zero, then there will be two real solutions.

Just plug in your values and you'll get the right answers.

Other Questions

What is 3/8 written as a percent? 3/8 = 0.375 * 100 = 37.5%

Factor completely 5a2 + b. Prime a(5a + b) b(5a2) ab(5a + 1)

The expression 1/2 times(4+8) represent the number of hours Mrs nakos work that last week of school.evaluate the expression to find the number of hours she works that week

What is the discount of a baseball hat that is $34 with a 28% discount?