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3 years ago

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Mrs Katie constructs a cube with 512 magnetic block students and her two classes will each make an identical cube. There are 28

students in one class and 25 students in the other class. How many blocks dies she need got all her students?

1 answer:

devlian [24]3 years ago

6 0

I take it each student is going to make a block.
She has 25 + 28 students all together which is 53 students total
Each one requires 512 magnetic blocks

Therefore she needs 53 * 512 = 27136 blocks.

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Ed is 7 years older than Ted. Ed’s age is also 3/4 times Ted’s age. How old are Ed and Ted?

svetlana [45]

Let Ted be x.

Ed is 7 years older = x + 7

Ed = (3/4)Ted

(x + 7) = (3/4)x

x + 7 = 3x/4

x - 3x/4 = -7

x/4 = -7

x = -28, Ted = -28 years.

(x + 7) = -28 + 7 = -21, Ed = -21 years

Goodness. We had negative numbers for the ages, well does that make sense? No it doesn't.

Our answer is correct. But the sense in the question is lacking. The question has been wrongly set.

<span>We might assume negative ages to mean before they came into the world, before birth! </span>

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3 years ago

211135.711111 write this in cash price (dollars)

aleksklad [387]

211,135.71 merry christmas

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2 years ago

You want to obtain a sample to estimate a population proportion. At this point in time, you have no reasonable estimate for the

Vesna [10]

Answer:

A sample size of at least 1,353,733 is required.

Step-by-step explanation:

In a sample with a number n of people surveyed with a probability of a success of , and a confidence level of , we have the following confidence interval of proportions.

$\pi \pm z\sqrt{\frac{\pi(1-\pi)}{n}}$

In which

z is the zscore that has a pvalue of .

The margin of error is:

$M = z\sqrt{\frac{\pi(1-\pi)}{n}}$

98% confidence level

So $\alpha = 0.02$ , z is the value of Z that has a pvalue of $1 - \frac{0.02}{2} = 0.99$ , so $Z = 2.327$ .

You would like to be 98% confident that you esimate is within 0.1% of the true population proportion. How large of a sample size is required?

We need a sample size of at least n.

n is found when M = 0.001.

Since we don't have an estimate for the proportion, we use the worst case scenario, that is $\pi = 0.5$

So

$M = z\sqrt{\frac{\pi(1-\pi)}{n}}$

$0.001 = 2.327\sqrt{\frac{0.5*0.5}{n}}$

$0.001\sqrt{n} = 2.327*0.5$

$\sqrt{n} = \frac{2.327*0.5}{0.001}$

$(\sqrt{n})^{2} = (\frac{2.327*0.5}{0.001})^{2}$

$n = 1353732.25$

Rounding up

A sample size of at least 1,353,733 is required.

5 0

3 years ago

A random variable x takes four possible values, 0, 2, a, and b, where a and b are unknown numbers. if pr[x = 0] = 0.2, pr[x=2] =

Alexus [3.1K]

$\displaystyle\sum_{x\in\{0,2,a,b\}}\mathbb P(X=x)=1$
$\mathbb P(X=0)+\mathbb P(X=2)+\mathbb P(X=a)+\mathbb P(X=b)=1$
$0.2+0.4+0.3+\mathbb P(X=b)=1$
$\implies\mathbb P(X=b)=0.1$

$\mathbb E(X)=\displaystyle\sum_{x\in\{0,2,a,b\}}x\mathbb P(X=x)=2.8$
$0\mathbb P(X=0)+2\mathbb P(X=2)+a\mathbb P(X=a)+b\mathbb P(X=b)=2.8$
$0.8+0.3a+0.1b=2.8$
$0.3a+0.1b=2$

$a+b=6\implies0.3a+0.1b=0.2a+0.1(6)=2$
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3 years ago

Number has more than two factors

VMariaS [17]

I'm going to assume that you are asking how a number can have two factors.
So, a factor is an integer (non-fractional/decimal number) you multiply by another integer to get the actual number.

Well, let's look at the number 4. The number four has the following factors:
1, 2, 4
In a 'rainbow' style, you match the two outer numbers, then the two next inner numbers, and so on.
Because the number '2' is the one in the center and there is no other number to multiply it by, it must multiply by itself to reach the number 4.
Well, you must have two numbers to actually multiply together, so every number has two factors: 1, and itself (except for 0).
I hope this helps, and good luck :)

7 0

3 years ago

Read 2 more answers