The lightbulbs used to provide exterior lighting for a large office building have an average lifetime of 600 hr. If length of life is approximately normally distributed with a standard deviation of 40 hr, how often should all the bulbs be replaced so that no more than 25% of the bulbs will have already burned out

can you add an image ?

step-by-step explanation:

option c) graph of line going through 1, 4 and 3, 10

step-by-step explanation:

let y equal to margo's coin collection

let x equal to number of years

at the begining x=0, y=1 → point=(x,y)→point=(0,1)

she adds 3 coins per year, then y=1+3x

at x=1, y=1+3(1)=1+3→y=4→point=(x,y)→point=(1,4)

at x=3, y=1+3(3)=1+9→y=10→point=(x,y)→point=(3,10)

the graph of line going through (1, 4) and (3, 10), then the option c is the correct.