$\displaystyle V(X) = E\left((X-E(X))^2\right) = E(X^2) - E(X)^2 \\\\ E(X^2) = \sum_{x\in\{1,2,3,4\}}x^2\,P(X=x) = 1^2\times0.4 + 2^2\times0.1 + 3^2\times0.3 + 4^2\times0.2 = 6.7 \\\\ \implies V(X) = 6.7 - 2.3^2 = \boxed{1.41}$

Standard deviation:

$\sigma_X = \sqrt{V(X)} = \sqrt{1.41} \approx \boxed{1.19}$

5 0

3 years ago

The triangles are isosceles and Î´abc : Î´jkl. what is the length of ?

umka2103 [35]

Length of.............. ? what...

Ima say length is 69

7 0

4 years ago

I really need help with this

Andreyy89

Answer:

x = 67

Step-by-step explanation:

If the measure of the entire chord is 166°, then if you add the two angles that form it together, it will equal 166.

So,

x + 15 + x + 17 = 166

Simplify.

2x + 32 = 166

Subtract 32 from both sides.

2x = 134

Divide both sides by 2.

x = 67

I hope this helps! Feel free to ask any questions!

3 0

3 years ago