Kelly’s first four test grades of the period were 80, 72, 96, and 88. Which inequality represents the grades she can earn on the fifth test to have a test average of no less than 80? g less-than-or-equal-to 16
g greater-than-or-equal-to 16
g less-than-or-equal-to 64
g greater-than-or-equal-to 64

x ≥ 64

Step-by-step explanation:

We want to find the average

Let x be the 5th grade

We want it to be no less than 80

Add up the scores and divide by 5

( 80+ 72+ 96+ 88+x)/5 ≥ 80

Combine like terms

( 336+x) /5 ≥ 80

Multiply each side by 5

336+x ≥ 400

Subtract 336 from each side

x ≥ 400-336

x ≥ 64

step-by-step explanation:

step-by-step explanation:

the original amount doesn't ''re just looking for the time it takes for 1/2 of the substance to we have

(1/2) =)     take the ln   of both sides

ln (1/2)   = )   and we can write

ln(1/2) = ) lne     and lne   = 1     so we have

ln(1/2) = -.1092t     divide both sides by -.1092

t = ln(1/2)/-.1092 = about 6.347 days = about 6.3 days (rounded)