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4 years ago

14

Please Help!!! 50 Points!!!!

2 answers:

Y_Kistochka [10]4 years ago

7 0

Answer:

156

Working:

Multiply 12 * 6.5 = 78. Then *2 to find the meters = 156

[If this is wrong, don't leave a rude comment! Message me and I will try to correct it.]

kupik [55]4 years ago

6 0

Answer:45

Step-by-step explanation:

You might be interested in

Evaluate 1^3 + 2^3 +3^3 +.......+ n^3

Molodets [167]

Notice that

$(n+1)^4-n^4=4n^3+6n^2+4n+1$

so that

$\displaystyle\sum_{i=1}^n((n+1)^4-n^4)=\sum_{i=1}^n(4i^3+6i^2+4i+1)$

We have

$\displaystyle\sum_{i=1}^n((i+1)^4-i^4)=(2^4-1^4)+(3^4-2^4)+(4^4-3^4)+\cdots+((n+1)^4-n^4)$

$\implies\displaystyle\sum_{i=1}^n((i+1)^4-i^4)=(n+1)^4-1$

so that

$\displaystyle(n+1)^4-1=\sum_{i=1}^n(4i^3+6i^2+4i+1)$

You might already know that

$\displaystyle\sum_{i=1}^n1=n$

$\displaystyle\sum_{i=1}^ni=\frac{n(n+1)}2$

$\displaystyle\sum_{i=1}^ni^2=\frac{n(n+1)(2n+1)}6$

so from these formulas we get

$\displaystyle(n+1)^4-1=4\sum_{i=1}^ni^3+n(n+1)(2n+1)+2n(n+1)+n$

$\implies\displaystyle\sum_{i=1}^ni^3=\frac{(n+1)^4-1-n(n+1)(2n+1)-2n(n+1)-n}4$

$\implies\boxed{\displaystyle\sum_{i=1}^ni^3=\frac{n^2(n+1)^2}4}$

If you don't know the formulas mentioned above:

The first one should be obvious; if you add $n$ copies of 1 together, you end up with $n$ .
The second one is easily derived: If $S=1+2+3+\cdots+n$ , then $S=n+(n-1)+(n-2)+\cdots+1$ , so that $2S=n(n+1)$ or $S=\dfrac{n(n+1)}2$ .
The third can be derived using a similar strategy to the one used here. Consider the expression $(n+1)^3-n^3=3n^2+3n+1$ , and so on.

7 0

4 years ago

33. Suppose that the scores on a statewide standardized test are normally distributed with a mean of 78 and a standard deviation

tino4ka555 [31]

Given the scores on a statewide standardized test are normally distributed

Mean = μ = 78

Standard deviation = σ = 3

Normalize the data using the z-score by using the following formula and chart:

$z=\frac{x-\mu}{\sigma}$

Estimate the percentage of scores of the following cases:

(a) between 75 and 81

so, the z-score for the given numbers will be:

$\begin{gathered} 75\rightarrow z=\frac{75-78}{3}=\frac{-3}{3}=-1 \\ 81\rightarrow z=\frac{81-78}{3}=\frac{3}{3}=1 \end{gathered}$

As shown, the percentage when (-1 < z < 1) = 68%

(b) above 87

$87\rightarrow z=\frac{87-78}{3}=\frac{9}{3}=3$

The percentage when (z > 3) = 0.5%

(c) below 72

$72\rightarrow z=\frac{72-78}{3}=\frac{-6}{3}=-2$

The percentage when (z < -2) = 0.5 + 2 = 2.5%

(d) between 75 and 84

$\begin{gathered} 75\rightarrow z=\frac{75-78}{3}=-\frac{3}{3}=-1 \\ 84\rightarrow z=\frac{84-78}{3}=\frac{6}{3}=2 \end{gathered}$

The percentage when ( -1 < z < 2 ) = 68 + 13.5 = 81.5%

3 0

1 year ago

Suppose a triangle has sides a, b, and c, and let be the angle opposite the side of length a. If cos > 0, what must be true?

frez [133]

A
hivbbv v b how old am i

6 0

3 years ago

Please help with number 7!

docker41 [41]

Answer:

He needs at 79

Step-by-step explanation:

He will be taking 6 quizzes.

Let x be the score on the final quiz

The average is found when we add up all the scores and divide by the number of scores

Average = (88+100+95+78+88+x) /6

The average is 88

88 = (88+100+95+78+88+x) /6

Multiply by 6 on each side

88*6 = (88+100+95+78+88+x) /6 *6

528 = (88+100+95+78+88+x)

Combine like terms

528 = 449+x

Subtract 449 from each side

528-429 = 449-449+x

79 =x

He needs at 79

8 0

4 years ago

Simplify to create an equivalent expression 19−6(−k−2)

lesya [120]

Answer:

boots and cuts

Step-by-step explanation:

5 0

3 years ago