Ask question

Ask question

All categories

2 years ago

5

A family reduced its normal monthly gas bill of 70$ by 9$ . What percent decrease does this represent ? Round to the nearest ten

th of a percent

1 answer:

BigorU [14]2 years ago

5 0

Answer:

12.9%

Step-by-step explanation:

$\frac{9}{70}*100\%\\\approx 12.9 \%$

You might be interested in

Find the mean, variance &a standard deviation of the binomial distribution with the given values of n and p.

MrMuchimi

A random variable following a binomial distribution over $n$ trials with success probability $p$ has PMF

$f_X(x)=\dbinom nxp^x(1-p)^{n-x}$

Because it's a proper probability distribution, you know that the sum of all the probabilities over the distribution's support must be 1, i.e.

$\displaystyle\sum_xf_X(x)=\sum_{x=0}^n\binom nxp^x(1-p)^{n-x}=1$

The mean is given by the expected value of the distribution,

$\mathbb E(X)=\displaystyle\sum_xf_X(x)=\sum_{x=0}^nx\binom nxp^x(1-p)^{n-x}$
$\mathbb E(X)=\displaystyle\sum_{x=1}^nx\frac{n!}{x!(n-x)!}p^x(1-p)^{n-x}$
$\mathbb E(X)=\displaystyle\sum_{x=1}^n\frac{n!}{(x-1)!(n-x)!}p^x(1-p)^{n-x}$
$\mathbb E(X)=\displaystyle np\sum_{x=1}^n\frac{(n-1)!}{(x-1)!((n-1)-(x-1))!}p^{x-1}(1-p)^{(n-1)-(x-1)}$
$\mathbb E(X)=\displaystyle np\sum_{x=0}^n\frac{(n-1)!}{x!((n-1)-x)!}p^x(1-p)^{(n-1)-x}$
$\mathbb E(X)=\displaystyle np\sum_{x=0}^n\binom{n-1}xp^x(1-p)^{(n-1)-x}$
$\mathbb E(X)=\displaystyle np\sum_{x=0}^{n-1}\binom{n-1}xp^x(1-p)^{(n-1)-x}$

The remaining sum has a summand which is the PMF of yet another binomial distribution with $n-1$ trials and the same success probability, so the sum is 1 and you're left with

$\mathbb E(x)=np=126\times0.27=34.02$

You can similarly derive the variance by computing $\mathbb V(X)=\mathbb E(X^2)-\mathbb E(X)^2$ , but I'll leave that as an exercise for you. You would find that $\mathbb V(X)=np(1-p)$ , so the variance here would be

$\mathbb V(X)=125\times0.27\times0.73=24.8346$

The standard deviation is just the square root of the variance, which is

$\sqrt{\mathbb V(X)}=\sqrt{24.3846}\approx4.9834$

7 0

3 years ago

Please help i am very confused

Step2247 [10]

Answer:

$\sqrt{80}$

80 is the number in the square root

Step-by-step explanation:

$d = \sqrt{(x_{2}-x_{1} )^{2} +(y_{2}-y_{1} )^{2} } \\d = \sqrt{(4-(-4) )^{2} +(5- 1 )^{2} }\\d = \sqrt{(4+4 )^{2} +4^{2}\\d = \sqrt{8^{2} +4^{2} }\\d=\sqrt{64 +16}\\d=\sqrt{80}$

4 0

2 years ago

Part C<br> If you use 10^-4 as the power of 10, what is the mass of an average grain of rock salt?

sleet_krkn [62]

Answer:

120 x 10^-4

Step-by-step explanation:Multiplying 1.2 by 10^2 and multiplying 10^-2 by 10^-2.Gives 120 x 10^-4 So, the mass of an average grain of rock salt is 120 x 10^-4 .

6 0

3 years ago

What do I do to get the answer and explain step by step!

abruzzese [7]

Answer:24

Step-by-step explanation: 1/6 multaplication. if you multiply 1/6 1 at a time, it increases 1/6 by 1/6 more. If we do this 24 times, we get 4. i know its complicated, but i tried explaining it in my own way. Hope it helps!

7 0

2 years ago

Fed [463]

Answer:

c) 15m + 2n

Step-by-step explanation:

8m+4n+7m−2n

Combine like terms

8m+7m +4n−2n

15m +2n

5 0

3 years ago

Read 2 more answers