An engineer wishes to determine the width of a particular electronic component. If she knows that the standard deviation is 2.9 mm, how many of these components should she consider to be 95%
sure of knowing the mean will be within +0.6 mm?
O 64
0 755
O 29
0 90
O 10

step-by-step explanation:

there is only one way to arrange all the eight relative to each other because they are not distinct. we have

now there are nine places to place an (and not more than one in one place).   because we have four symbols, we need to choose four of these nine places to insert an . order does not matter because the are not distinct.

thus there are 1 · c(9,4) ways, or, if we calculate it,

thus there are 126 ways to form such "words."