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tankabanditka [31]
3 years ago
10

75000 live bacteria present in a culture in a flask. When antibiotic is added to the culture, the number of live bacteria is red

uced by half every four hours. Approximately how many hours have passed when there are 1500 bacteria left alive?
A. 22.3 hours
B. 22.6 hours
C. 22.9 hours
D. 22.2 hours
Mathematics
2 answers:
posledela3 years ago
3 0
The number of bacteria at any time t where t is number of hours is given by the equation,
                                At = Ao(1/2)^t/4
where Ao is the original number of bacteria. Substituting the known values from the equation,
                                1500 = (75000)(0.5)^t/4
The value of t from the equation is equal to 22.57 hours. 
hammer [34]3 years ago
3 0

Answer: 22.6

Step-by-step explanation:

apex

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Polygon ABCD is reflected and dilated to give polygon PQRS. The coordinates of the preimage are (2, 2), (6, 8), (12, 8), and (16
HACTEHA [7]

Answer: The scale factor of the dilation is 0.5.

Explanation:

It is given that ABCD is polygon which is reflected and dilated , then we get PQRS.

The vertices of ABCD are (2, 2), (6, 8), (12, 8), and (16, 2) respectively. The vertices of image  PQRS are (11, 15),(9, 12), (6, 12), and (4, 15) respectively.

The reflection affects the coordinates but does not affect the length of the sides.

But when we talk about dilation it affects the length of sides according to the scale factor or a constant factor.

If a line segment AB is dilated by scale factor k then length of A'B' is k times length of AB.

|A'B'|=k\times |AB|   .... (1)

So we have to find any side length of preimage and the side length of that side in image. it means we have to find AB and PQ.

Use distance formula to find the side length.

D=\sqrt{(x_2-x_1)^2+(y_2-y_1)^2}

AB=\sqrt{(8-2)^2+(6-2)^2}=\sqrt{36+16}=2\sqrt{13}

PQ=\sqrt{(9-11)^2+(12-15)^2}=\sqrt{4+9}=\sqrt{13}

It is noticed that the size of side in preimage is 2\sqrt{13} and the size of same side in image is \sqrt{13}.

Using equation (1), we get

\sqrt{13}=k \times 2\sqrt{13}

k=\frac{1}{2}

k=0.5

Hence, the value of scale factor is 0.5.

7 0
3 years ago
Read 2 more answers
Quadratic equations Please Help Me!!!!!!
igor_vitrenko [27]

The roots are 1 +√7 and 1 -√7.

<h3>What is Quadratic equation?</h3>

A quadratic equation in the variable x is an equation of the form ax² + bx + c= 0, where a, b, c are real numbers, a≠0

Given equation:

y= x²+2x-6

First,

Half the coefficient of x and add and subtract the square of (b/2)

y= x²+2x-6+(1)²-(1)²

y= x²+2x+(1)² -6 -(1)²

y= (x+1)² -7

Now, equate y=0

(x+1)² -7 =0

(x+1)² = 7

x+1= ±√7

x=1 ±√7

Hence, the roots are 1 +√7 and 1 -√7.

Learn more about quadratic equation here:

brainly.com/question/1962219

#SPJ1

7 0
1 year ago
In the given figure, find ∠PQS, if∠PQR = 5x + 25 and∠SQR = 2x + 10.
kramer

Answer:

∠PQS= 3(x +5)

Step-by-step explanation:

∠PQR = 5x + 25

∠SQR+∠PQS= 5x+25

∠PQS = ∠PQR-∠SQR

∠PQS= (5x + 25 )-(2x + 10)

∠PQS = 5x+25 -2x-10

∠PQS= 3x +15

∠PQS= 3(x +5)

3 0
3 years ago
Which statement best discribe 3×8=8×3
never [62]

Answer:

<h2>the associative property</h2>

Step-by-step explanation:

the associative property, the order of the numbers does not change their product


3 * 8 = 8 * 3

24 = 24

3 0
3 years ago
A basket holds at most 14 pounds of apples and oranges
Helen [10]
A.

B and C are wrong because x is more than or equal to 3.

D is wrong because y is the weight of oranges and cannot be negative.
7 0
3 years ago
Read 2 more answers
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