Help fast I’m giving 20 points’ The number of bacteria in a petri dish is 42 and is tripling every month

hichkok12 [17]

$12 \frac{9}{150}=12 \frac{9 \div 3}{150 \div 3}=12 \frac{3}{50}=12\frac{3 \times 2}{50 \times 2}=12 \frac{6}{100}=\boxed{12.06}$

7 0

3 years ago

Find the surface area of the Rectangular Pyramid. Please see the attachment, of course 45 yards ^2 is not the correct answer. Th

zheka24 [161]

Answer:

Surface area = 39 yards²

Step-by-step explanation:

∵ the surface area of the pyramid = 1/2 pl + base area

Where p = perimeter of the base , l = slant height

∵ Area of the base = 3 × 3 = 9 yards²

∵ Perimeter of the base = 4 × 3 = 12 yards

∵ Slant height = 5 yards

∴ The surface area = 1/2 × 12 × 5 + 9 = 39 yards²

8 0

3 years ago

Read 2 more answers

X/5-2=x/2+3 solve for x

Makovka662 [10]

Solve for x:x/5 - 2 = x/2 + 3
Put each term in x/5 - 2 over the common denominator 5: x/5 - 2 = x/5 - (10)/5:x/5 - (10)/5 = x/2 + 3
x/5 - (10)/5 = (x - 10)/5:(x - 10)/5 = x/2 + 3
Put each term in x/2 + 3 over the common denominator 2: x/2 + 3 = x/2 + 6/2:(x - 10)/5 = x/2 + 6/2
x/2 + 6/2 = (x + 6)/2:(x - 10)/5 = (x + 6)/2
Multiply both sides by 10:(10 (x - 10))/5 = (10 (x + 6))/2
10/5 = (5×2)/5 = 2:2 (x - 10) = (10 (x + 6))/2
10/2 = (2×5)/2 = 5:2 (x - 10) = 5 (x + 6)
Expand out terms of the left hand side:2 x - 20 = 5 (x + 6)
Expand out terms of the right hand side:2 x - 20 = 5 x + 30
Subtract 5 x from both sides:(2 x - 5 x) - 20 = (5 x - 5 x) + 30
2 x - 5 x = -3 x:-3 x - 20 = (5 x - 5 x) + 30
5 x - 5 x = 0:-3 x - 20 = 30
Add 20 to both sides:(20 - 20) - 3 x = 20 + 30
20 - 20 = 0:-3 x = 30 + 20
30 + 20 = 50:-3 x = 50
Divide both sides of -3 x = 50 by -3:(-3 x)/(-3) = 50/(-3)
(-3)/(-3) = 1:x = 50/(-3)
Multiply numerator and denominator of 50/(-3) by -1:Answer: x = (-50)/3

7 0

2 years ago

PLEASE HELPPPPP

dsp73

Answer:

see explanation

Step-by-step explanation:

the equation of parabola in vertex form is

y = a(x - h)² + k

where (h, k ) are the coordinates of the vertex and a is a multiplier.

here (h, k ) = (3, 1 ) , then

y = a(x - 3)² + 1

to find a substitute any other point on the graph into the equation.

using (0, 7 )

7 = a(0 - 3)² + 1 ( subtract 1 from both sides )

6 = a(- 3)² = 9a ( divide both sides by 9 )

$\frac{6}{9}$ = $\frac{2}{3}$ = a

y = $\frac{2}{3}$ (x - 3)² + 1 ← in vertex form

------------------------------------------------------

the equation of a parabola in factored form is

y = a(x - a)(x - b)

where a, b are the zeros and a is a multiplier

here zeros are - 1 and 3 , the factors are

(x - (- 1) ) and (x - 3), that is (x + 1) and (x - 3)

y = a(x + 1)(x - 3)

to find a substitute any other point that lies on the graph into the equation.

using (0, - 3 )

- 3 = a(0 + 1)(0 - 3) = a(1)(- 3) = - 3a ( divide both sides by - 3 )

1 = a

y = (x + 1)(x - 3) ← in factored form

3 0

2 years ago

Our faucet is broken, and a plumber has been called. The arrival time of the plumber is uniformly distributed between 1pm and 7p

Ymorist [56]

Answer:

$E(A+B) = E(A)+E(B)=4+0.5 =4.5 hours$

$Var(A+B)= Var(A)+Var(B)=3+0.25 hours^2=3.25 hours^2$

Step-by-step explanation:

Let A the random variable that represent "The arrival time of the plumber ". And we know that the distribution of A is given by:

$A\sim Uniform(1 ,7)$

And let B the random variable that represent "The time required to fix the broken faucet". And we know the distribution of B, given by:

$B\sim Exp(\lambda=\frac{1}{30 min})$

Supposing that the two times are independent, find the expected value and the variance of the time at which the plumber completes the project.

So we are interested on the expected value of A+B, like this

$E(A +B)$

Since the two random variables are assumed independent, then we have this

$E(A+B) = E(A)+E(B)$

So we can find the individual expected values for each distribution and then we can add it.

For ths uniform distribution the expected value is given by $E(X) =\frac{a+b}{2}$ where X is the random variable, and a,b represent the limits for the distribution. If we apply this for our case we got: