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Mathematics

1 answer:

seropon [69]3 years ago

8 0

Answer:

46.78 PROBIBILITY

Step-by-step explanation:

MATHS

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-3(1-2x)-3=-20-8x what is the work and answer

larisa86 [58]

You have to keep order of operations in mind.

1. Take care of the parentheses; distribute.
-3+6x-3=-20-8x
Simplified: 6x-6=-20-8x

2. Isolate the x variable.
Add 8x to both sides and add 6 to both sides.
14x=-14

3. Solve for x.
Divide by 14 on both sides.
x=-1

4 0

3 years ago

The comprehensive strength of concrete is normally distributed with μ = 2500 psi and σ = 50 psi. Find the probability that a ran

VARVARA [1.3K]

Answer:

The probability that the diameter falls in the interval from 2499 psi to 2510 psi is 0.00798.

Step-by-step explanation:

Let's define the random variable, $X =$ "Comprehensive strength of concrete". We have information that $X$ is normally distributed with a mean of 2500 psi and a standard deviation of 50 psi (or a variance of 2500 psi). In other words, $X \sim N(2500, 2500)$ .

We want to know the probability of the mean of X or $\bar{X}$ that falls in the interval $[2499;2510]$ . From inference theory we know that :

$\bar{X} \sim N(2500, \frac{2500}{5}) \Rightarrow \bar{X} \sim N(2500,500)$

Now we can find the probability as follows:

$P(2499 \leq \bar{X} \leq 2510) \Rightarrow P(\frac{2499 - 2500}{500} \leq \frac{\bar{X} - 2500}{500} \leq \frac{2499 - 2500}{500} ) \Rightarrow\\\Rightarrow P(-0.002 \leq \frac{\bar{X} - 2500}{500} \leq 0.02 ) \Rightarrow P(-0.002 \leq Z \leq 0.02 )$