1. What is the simple interest on $4,500 for 2 and a half years at 4% per year?

MCR3U1 Culminating 2021.pdf

11111nata11111 [884]

Answer:

(a) $y = 350,000 \times (1 + 0.07132)^t$

(b) (i) The population after 8 hours is 607,325

(ii) The population after 24 hours is 1,828,643

(c) The rate of increase of the population as a percentage per hour is 7.132%

(d) The doubling time of the population is approximately, 10.06 hours

Step-by-step explanation:

(a) The initial population of the bacteria, y₁ = a = 350,000

The time the colony grows, t = 12 hours

The final population of bacteria in the colony, y₂ = 800,000

The exponential growth model, can be written as follows;

$y = a \cdot (1 + r)^t$

Plugging in the values, we get;

$800,000 = 350,000 \times (1 + r)^{12}$

Therefore;

(1 + r)¹² = 800,000/350,000 = 16/7

12·㏑(1 + r) = ㏑(16/7)

㏑(1 + r) = (㏑(16/7))/12

r = e^((㏑(16/7))/12) - 1 ≈ 0.07132

The model is therefore;

$y = 350,000 \times (1 + 0.07132)^t$

(b) (i) The population after 8 hours is given as follows;

y = 350,000 × (1 + 0.07132)⁸ ≈ 607,325.82

By rounding down, we have;

The population after 8 hours, y = 607,325

(ii) The population after 24 hours is given as follows;

y = 350,000 × (1 + 0.07132)²⁴ ≈ 1,828,643.92571

By rounding down, we have;

The population after 24 hours, y = 1,828,643

(c) The rate of increase of the population as a percentage per hour = r × 100

∴ The rate of increase of the population as a percentage = 0.07132 × 100 = 7.132%

(d) The doubling time of the population is the time it takes the population to double, which is given as follows;

Initial population = y

Final population = 2·y

The doubling time of the population is therefore;

$2 \cdot y = y \times (1 + 0.07132)^t$

Therefore, we have;

2·y/y =2 = $(1 + 0.07132)^t$

t = ln2/(ln(1 + 0.07132)) ≈ 10.06

The doubling time of the population is approximately, 10.06 hours.

8 0

2 years ago

Follow the process of completing the square to solve 2x2 + 8x - 12 = 0. After adding B2 to both sides of the equation in step 4,

valentina_108 [34]

2x2 + 8x - 12 = 0
4 + 8x - 12 = 0
8x = 12 - 4
8x = 8
x = 1

4 0

3 years ago

A car travels 279 miles in 4 1/2 hours. How many miles would the car travel in 12 hours? *

Liono4ka [1.6K]

Answer:

744 miles in 12 hours.

Step-by-step explanation:

MATH

4 0

2 years ago

between 1995 and 2006, the population of samburg, usa(in thousands) can be modeled by f(x) = 0.35x(squared) - 2.1x+15.8 where x=

Juli2301 [7.4K]

$\bf f(x)=0.35x^2-2.1x+15.8\qquad 
\begin{cases}
x=\textit{year since 1995}\\
f(x)=\textit{population amount}
\end{cases}$

the equation is a quadratic one, and it has a positive coefficient on the leading term, meaning, is opening upwards, so it has a "burrow" for the vertex.

the minimum or lowest point for a quadratic opening upwards is, well, the vertex point :), the "x" value is the year, the "y" or f(x) value is the population, we're asked for the year, or the x-coordinate of the vertex

well $\bf \begin{array}{llll}
f(x)=&0.35x^2&-2.1x&+15.8\\
&\quad \uparrow &\quad \uparrow&\uparrow \\
&\quad a&\quad b &c
\end{array}
\\\\

\\\\
\qquad \textit{vertex of a parabola}\\ \quad \\
\qquad 

\left(\boxed{-\cfrac{{{ b}}}{2{{ a}}}}\quad ,\quad {{ c}}-\cfrac{{{ b}}^2}{4{{ a}}}\right)$

5 0

3 years ago

Is the percent increase from 50 to 70 equal to the percent decrease from 70 to 50? Explain.

Salsk061 [2.6K]

Answer:

No

Step-by-step explanation:

Percent change is the difference in numbers divided by initial number converted to percent value.

Percent increase:

(70 - 50)/50*100% = 40%

Percent decrease:

(70 - 50)/70*100% = 28.57%

Compare:

40% ≠ 28.57%

4 0

2 years ago

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