So far in math class, a student's quiz scores are 86%, 82%, 72%, and 69%. what score does the student need on the fifth quiz to have a mean quiz score of 79%? all the quizzes have equal weights. a 86% b 77.25% c 79% d 87%

a

Step-by-step explanation:

the mean =

let the fifth score be x and count = 5, hence

= 79 ( multiply both sides by 5 )

309 + x = 395 ( subtract 309 from both sides )

x = 86

the student requires a score of 86% → a

the figures below are made out of circles, semicircles, quarter … find the area and the perimeter of each figure and give your answers as a completely simplified exact value in terms of π (no approximations). remember that we'll also have to cut whatever areas we get in half, since we're only dealing im pretty sure that is the right answer

step-by-step explanation:

reduce the friction between its moving parts

step-by-step explanation:

in fact, by reducing the friction between the moving parts of the machine, it is possible to reduce the energy wasted due to this friction; therefore, more input energy is converted into useful work, and this will improve the efficiency of the machine.