The answer can be readily calculated using a single variable, x:
Let x = the amount being invested at an annual rate of 10%
Let (8000 - x) = the amount being invested at an annual rate of 12%
The problem is then stated as:
(x * 0.10) + ((8000 - x) * 0.12) = 900
0.10(x) + ((8000 * 0.12) - 0.12(x)) = 900
0.10(x) + 960 - 0.12(x) = 900
0.10(x) - 0.12(x) = 900 - 960
-0.02(x) = -60
-0.02(x) * -100/2 = -60 * -100/2
x = 6000 / 2
x = 3000
Thus, $3,000 is invested at 10% = $300 annually; and $8,000 - $3,000 = $5,000 invested at 12% = $600 annually, which sum to $900 annual investment.
DC-10
At t=0 the altidude is 4500 feet
It's descending at a rate of 150 feet per minute, then each 5 minutes it descends (150 feet/min)(5 min)=750 feet. Then:
At t=5 the altitude is 4500 feet-750 feet=3750 feet
At t=10 the altitude is 3750 feet-750 feet=3000 feet
727
At t=0 the altidude is 600 feet
It's climbing at a rate of 75 feet per minute, then each 5 minutes it climbs (75 feet/min)(5 min)=375 feet. Then:
At t=5 the altitude is 600 feet+375 feet=975 feet
At t=10 the altitude is 975 feet+375 feet=1350 feet
The graph with these characteristics is Graph B.
Answer: The graph B shows when the two planes will be at the same altitude
81.
Add them all and then divide by the number of days (by 5)
$430 because you divide 15,480 divided by 36 and get your answer