The sum 1 and 6 divide by 7

Mathematics

1 answer:

klio [65]4 years ago

4 0

(1 + 6)/7

1+6=7

7/7

Answer: 1

Note: add then ➗

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Math help guys how wouls i work this out

Andrei [34K]

8 > 7 + $\frac{x}{6}$ Subtract 7 from both sides

1 > $\frac{x}{6}$ Multiply both sides by 6

6 > x Flip it around so it's easier to read

x < 6

You can graph your answer by drawing an open circle at the 6 and coloring the line to the left. The circle should be open, because x is <em>less than 6</em>, not less than or equal to. You would color to the left to show that x can be anything less than 6.

4 0

3 years ago

Suppose that the lifetime of tv tubes are normally distributed with a standard deviation of 1.1 years. Suppose that exactly 20%

IrinaK [193]

Answer:

4.924 years

Step-by-step explanation:

Lets denote X the lifetime of a tv tube (In years). X has distribution $N(\mu, 1.1)$ , with $\mu$ unknown.

We know that P(X < 4) = 0.2. Using this data, we can find the value of $\mu$ throught standarization.

Lets call $Z = \frac{X - \mu}{1.1}$ the standarization of X. Z has distribution N(0,1), and its cummulative function, $\phi$ is tabulated. The values of $\phi$ can be found in the attached file.

$P(X < 4) = P(\frac{X - \mu}{1.1} < \frac{4 - \mu}{1.1}) = P(Z < \frac{4 - \mu}{1.1}) = \phi(\frac{4 - \mu}{1.1}) = 0.2$

The value q such that $\phi (q) = 0.2$ doesnt appear on the table. We can find it by using the symmetry of the normal density function. The opposite of q, -q must verify that $\phi(-q) = 0.8$ , hence -q must be equal to 0.84. Thus, q = -0.84