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2 years ago

Ava, Zoe and Logan went to the market to buy some presents for a friend's birthday. The three of them

Mathematics

1 answer:

alexira [117]2 years ago

7 0

a + z + l = 720

l = 2z = 2a - 80

4z + 40 = 720

4z = 680

z = 170

l = 340

a = 210

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2x+5=11 two step equations

Sati [7]

Answer:

x=3

Explanation: 11-5=6

6/2= 3

Plug 3 into the equation and you get 2x3+5=11 which 2x3=6 and 6+5=11

4 0

3 years ago

I don’t understand number 5

yarga [219]

Multiply what’s on the outside to the inside, the variable is always a lower case letter such as x,

4 0

3 years ago

If the radius of the circle is multiplied by a factor of 3, then the area of the circle is multiplied by a factor of

Oksi-84 [34.3K]

$\bf \textit{area of a circle}\\\\
A=\pi r^2\quad 
\begin{cases}
r=radius\\
-----\\
r=\stackrel{r\times 3}{3r}
\end{cases}\implies A=\pi (3r)^2
\\\\\\
A=\pi (3^2r^2)\implies A=9(\pi r^2)$

notice, if the original area was πr², then the new area has a factor in front of it, that much.

8 0

3 years ago

When Carson runs the 400 meter dash, his finishing times are normally distributed with a mean of 63 seconds and a standard devia

Gnom [1K]

Answer: in 95% of races, his finishing time will be between 62 and 64 seconds.

Step-by-step explanation:

The empirical rule states that for a normal distribution, nearly all of the data will fall within three standard deviations of the mean . The empirical rule is further illustrated below

68% of data falls within the first standard deviation from the mean.

95% fall within two standard deviations.

99.7% fall within three standard deviations.

From the information given, the mean is 63 seconds and the standard deviation is 5 seconds.

2 standard deviations = 2 × 0.5 = 1

63 - 1 = 62 seconds

63 + 1 = 64 seconds

Therefore, in 95% of races, his finishing time will be between 62 and 64 seconds.

6 0

3 years ago

At 10 percent interest, how long does it take to quadruple your money?

horsena [70]

It takes about 14.55 years for quadruple your money

Solution:

Given that,

At 10 percent interest, how long does it take to quadruple your money

Rule of 144:

The Rule of 144 will tell you how long it will take an investment to quadruple

Here,

Rate of interest = 10 %

Therefore, number of years to quadruple your money is obtained by dividing 144 by 10

Rule of 144 Formula:

$N = \frac{144}{R}$

Where:

N = Number of many years times.

144 = Is the constant variable.

R = Rate of interest.

$\rightarrow N = \frac{144}{10} = 14.4$

Thus it takes about 14.4 years for quadruple your money.

Another method:

If initial amount is $ 1 and it if quadruples it should be $ 4

We have to find the number of years if rate of interest is 10 %

Let "n" be the number of years

Then we can say,

$Amount = Principal(1+\frac{R}{100})^n$

$4 = 1(1+\frac{10}{100})^n$

$4 = 1(1+0.1)^n\\\\4= 1(1.1)^n\\\\4 = 1.1^n\\\\We\ know\ that,\\\\(1.1)^{14.55} = 1.1^n\\\\We\ know\ that\\\\If\ a^m = a^n\ then\ m = n\\\\Therefore,\\\\14.55 = n\\\\n = 14.55$

Thus Option D 14.55 years is correct

7 0

4 years ago