Phil has 50 nickels and dimes worth $4.15. How many dimes does he have

Mathematics

1 answer:

Katen [24]3 years ago

7 0

Answer: Phil has 33 dimes, and 17 nickels

Step-by-step explanation:

Let number of nickels be X, and dimes be Y.

X + Y = 50.

Since nickels stand for 5 cents, or 0.05 dollars, and dimes are 10 cents, or 0.10 dollars, we can also write the total worth as:

0.05*X + 0.10*Y = 4.15

Multiply this last equation by 20:

20*0.05*X + 20*0.10*Y = 20*4.15

Simplify:

X + 2*Y = 83

Subtract the first equation (X + Y = 50) from this one:

Y = 33.

Thus Phil has 33 dimes, and 17 nickels.

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Part 2: The Zombie Assassin

Tatiana [17]

Answer: See below

Step-by-step explanation:

y = a(b)ˣ

y: final population of zombies
a: initial population of zombies
b: rate of decrease
x: number of hours

Given: a = 500,000 b = 50% (0.5)

y = 500,000(0.5)ˣ

Since we want to know the number assassinated (A), subtract the total from the final population of zombies

A = 500,000 - y

a) Equation: 500,000 - 500,000(0.5)ˣ

$\begin{array}{c|c|c||l|c}\underline{\quad a\quad}&\underline{\quad b\quad}&\underline{\quad x\quad}&\underline{\quad 500,000(0.5)^x=y \qquad}&\underline{\quad 500,000-y=A\quad}\\500,000&0.5&5&500,000(0.5)^5=15,625&\bold{484,375}\\500,000&0.5&10&500,000(0.5)^{10}=488&\bold{499,512}\\500,000&0.5&15&500,000(0.5)^{15}=15&\bold{499,985}\\500,000&0.5&20&500,000(0.5)^{20}=0&\bold{500,000}\\\end{array}$