A sample of N = 9 students has aΣX = 52 and ΣX2= 322. For this sample, what is the standard deviation? Use the formula shown below. BE SURE TO ROUND OFF ALL DECIMALS TO 2 DECIMAL PLACES.

Wo audio speakers are placed on a vertical rail. speaker a is placed at head-level while speaker b is place at some variable height, \delta yδy, above speaker a. both speakers receive simultaneous input from a sine-wave generator so the speakers each produce a pure sinusoidal sound wave with a wavelength of 0.531 meters. calculate the lowest height that speaker b can be placed above speaker a to produce a minimum of sound heard by person standing \delta x = 7.86δx=7.86 meters directly in front of speaker a.

Select the correct answer. anna will wear a black dress when she attends het cousin's wedding. which color(s) does the dress absorb? a. all colors b. no colors c. red and green d. white

Consider a double atwood machine constructed as follows: a mass 4m is suspended from a string that passes over a massless pulley on frictionless bearings. the other end of this string supports a second similar pulley, over which passes a second string supporting a mass of 3m at one end and m at the other. using two suitable generalized coordinates, set up the lagrangian and use the lagrange equations to find the acceleration of the mass 4m when the system is released. explain why the top pulley rotates even though it carries equal weights on each side.