All categories

3 years ago

can u tell me what this is plz, I think I have worked it out but don't know if it is right: decrease £60 by 20%

Mathematics

2 answers:

aalyn [17]3 years ago

7 0

48. 20% of 60 euros would be 12 euros. Decreasing it means to subtract, so 60 - 12 = 48

BlackZzzverrR [31]3 years ago

3 0

The answer would be £48 because if you divide 60 by 5, you get 12. 4/5 would be 48, or a twenty percent decrease.

You might be interested in

Is 4/3y=x a direct variation?

Masja [62]

Answer:

1 yes 2 no 3 no

Step-by-step explanation:

7 0

3 years ago

Read 2 more answers

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

54,000,000=5.4·10^n<br><br> HELP

kolezko [41]

Step-by-step explanation:

$54,000,000 = 5.4 \times {10}^{7} \\$

6 0

3 years ago

Solve the following system of equations.

Elan Coil [88]

Answer:

(2,-3)

Step-by-step explanation:

I am not sure if you meant the first equation to be y or -y. I solved it as y.

y = x-5 -x -3y =7

I am going to take the second equation and write it as x =

-x - 3y = 7 Give equation

-x = 3y +7 Add 3y to both sides

x = -3y-7 Multiplied each term in the equation by -1 so that x could be positive

I am going to substitute -3y-7 for x in the first equation up above

y = x - 5

y = -3y -7 - 5 Substitute -3y-7 for x

y = -3y -12 Combined -7-5

4y = -12 Added 3y to both sides

y = -3 Divided both sides by 4.

I now know that y is -3, I will plug that into x = -3y-7 to solve for x

x = -3(-3) -7

x = 9-7 A negative times a negative is a positive

x = 2

5 0

1 year ago

A contractor digs a hole for the basements of a new house that is 40 feet long and 10 1/2 feet deep. What is the width of the ho

34kurt

D. 15.5

40*10.5 = 420

6510/420 = 15.5

7 0

3 years ago