Will give the brainliest to the person who answers the question first and correctly!! For the data set 4, 5, 10, 11, 15, the mean, x, is 9. What is the standard deviation?

Round to the nearest tenth.

A. 4.1

B. 20.5

C. 16.4

D. 4.5

Complete the solution of the equation. find the value of y when x equals -5. -4x - 8y = -52

With these 5 geometry questions! pls 1.)quadrilateral abcd is inscribed in this circle.what is the measure of ∠a ? enter your answer in the box.°2.)quadrilateral abcd is inscribed in a circle.what is the measure of angle a? enter your answer in the box.m∠a= 3.)quadrilateral abcd is inscribed in this circle.what is the measure of angle b? enter your answer in the box.m∠b= °4.)quadrilateral abcd is inscribed in this circle.what is the measure of angle a? enter your answer in the box.°5.) quadrilateral abcd is inscribed in this circle.what is the measure of angle c? enter your answer in the box.°

Express -5 2/5 as an improper fraction.