The four sides of a printed circuit board (PCB) enclosure consist of two pieces selected from a population whose mean length is 30 cm with standard deviation 0.14, and two pieces selected from a population whose mean length is 45 cm with standard deviation 0.31 cm. Assuming the four pieces are chosen independently, the standard deviation of the perimeter is

Step-by-step explanation:

let X1,X2 represents the length of two pieces selected from a population

the mean and standaerd deviation for the length of these two pieces X1,X2 is 30 cm and 0.14 cm

 

let X2,X3 represents the length of two pieces selected from a population

the mean and standaerd deviation for the length of these two pieces X2,X3 is 45 cm and 0.31 cm

To be continued on the attachment:

The answer is 270 cars.you can do this by making a proportional relationship. for instance, 200 is the whole we are using, so on a “number line” 200 would be over 100%. now, since he sells 35% more, add 35% to 100% to get 135% on the other side of the “number line” on the bottom half, leaving the top half empty.cross multiply 200 by 135 then divide by 100 to get your answer. i hope this , if it did, , if you don’t mind, giving me brainiest! 200/100% } 200 • 135 /100 ? /135%