Answer:
a(7) = 21
Step-by-step explanation:
Using the recursive formula and a(1) = 0, a(2) = 1 , then
a(3) = a(2) + 2a(1) = 1 + 2(0) = 1 + 0 = 1
a(4) = a(3) + 2a(2) = 1 + 2(1) = 1 + 2 = 3
a(5) = a(4) + 2a(3) = 3 + 2(1) = 3 + 2 = 5
a(6) = a(5) + 2a(4) = 5 + 2(3) = 5 + 6 = 11
a(7) = a(6) + 2a(5) = 11 + 2(5) = 11 + 10 = 21
Answer:
For every 5 female birds in the pet store, there are 3 male birds.
Step-by-step explanation:
Ratios are used to represent a proportion. In this case, we are comparing female and male birds. So, since female is 5 and male is 3, the ratio is 5:3
[3(3)-4][2^2]
=20
The answer is 20.
Let a be the amount needed of 70% pure antifreeze, and let b be the amount needed of 95% pure antifreeze.
0.7a + 0.95b = 180 * 0.9 .........(1)
a + b = 180 .............................(2)
b = 180 - a ..............................(3)
Plugging the expression for b in equation (3) into equation (1), we get:
0.7a + 0.95(180 - a) = 162 ......(4)
Solving equation (4) gives the value a = 36, and plugging this value for a into equation (2) we get b = 144.
Amounts needed are therefore 36 gallons of 70% pure antifreeze and 144 gallons of 95% pure antifreeze.
