The rational number would be 16
She used 54 inches. 3/4 is equal to .75 so you can find 3/4 of the board by taking the fool length and multiplying it by .75 so 6•.75=4.5. So 3/4 of the board is 4.5 ft. However, the answer has to be in inches so since there are 12 inches in a foot you multiply 4.5•12 and that gives you your answer:54 inches.
C(x) = 400 + 20x - 0.2x²
c(30) = 400 + 20(30) - 0.2(30)²
= 400 + 600 - 0.2(900)
= 1000 - 180
= 820
It costs $820 when 30 radios are produced.
Marginal cost is how much it would cost to make one MORE of the same product so now we find how much it costs to produce 31 radios and compare the two.
c(31) = 400 + 20(31) - 0.2(31)²
= 400 + 620 - 0.2(961)
= 1020 - 192.2
= 827.8 or ≈828.
Now we find the difference which means we subtract the two.
828 - 820 = 8.
Your marginal cost is $8.
To compare we can also do 29 radios.
c(29) = 400 + 20(29) - 0.2(29)² = 811.8 or ≈812
820 - 812 = 8.
X represents the amount of children's tickets
y represents the amount of adult's tickets
8(x+y) = 54
