HELPPPP!!!! ASAPPPP!!!

A=1/2f(r+z), solve for r

marin [14]

Answer: $\frac{2A}{f} -2=f$

Step-by-step explanation:

A=1/2(r+2)

2A=f(r+2)

2A/f=r+2

2A/f-2=r

7 0

2 years ago

runben sees 14 wheels on a total of 6 bicycles and tricycles how many bicycles and tricycles are there

olganol [36]

Answer:

B = 4

T = 2

Step-by-step explanation:

First, figure out the equation.

We know that bicycles have 2 wheels, that there are 3 on a tricycle, and there are a total of 14 wheels and a total of 6 bicycles and tricycles.

Let b stand for bicycles and t stand for tricycles:

14 = 2b + 3t

6 = b + t

We can figure out the amount of either by rearranging the second equation to isolate one variable. I will solve it in two ways

In the first way, I will solve for b

(-t) 6 = b + t (-t)

6 - t = b

Plug this into the first equation and solve for remaining variable

14 = 2(6 - t) +3t

14 = 12 - 2t + 3t

14 = 12 +t

-12 -12

2 = t

6 - 2 = b

b = 4

The second way was to solve for t first

(-b) 6 = b + t (-b)

6 - b = t

14 = 2b + 3(6 - b)

14 = 2b + 18 - 3b

(-18) 14 = 18 -b (-18)

-4/-1 = -b/-1

b = 4

6 - 4 = t

t = 2

It doesn't matter which way you go, they both give you the exact same answer.

Sooo, recap!

1) write equations

2) switch the easier of the two to isolate one variable

3) substitute to find other variable (x2)

4) Find answers! =D

Hope this helps!

8 0

3 years ago

According to the National Bridge Inspection Standard (NBIS), public bridges over 20 feet in length must be inspected and rated e

slamgirl [31]

Answer:

1.80% probability that in a random sample of 12 major Denver bridges, at least 4 will have an inspection rating of 4 or below in 2020.

Step-by-step explanation:

For each bridge, there are only two possible outcomes. Either it has rating of 4 or below, or it does not. The probability of a bridge being rated 4 or below is independent from other bridges. So we use the binomial probability distribution to solve this problem.

Binomial probability distribution

The binomial probability is the probability of exactly x successes on n repeated trials, and X can only have two outcomes.

$P(X = x) = C_{n,x}.p^{x}.(1-p)^{n-x}$

In which $C_{n,x}$ is the number of different combinations of x objects from a set of n elements, given by the following formula.

$C_{n,x} = \frac{n!}{x!(n-x)!}$

And p is the probability of X happening.

For the year 2020, the engineers forecast that 9% of all major Denver bridges will have ratings of 4 or below.

This means that $p = 0.09$

Use the forecast to find the probability that in a random sample of 12 major Denver bridges, at least 4 will have an inspection rating of 4 or below in 2020.

Either less than 4 have a rating of 4 or below, or at least 4 does. The sum of the probabilities of these events is 1.

So

$P(X < 4) + P(X \geq 4) = 1$