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Nitella [24]
3 years ago
8

e lifetimes of lightbulbs of a particular type are normally distributed with a mean of290 hours and astandard deviation of6 hour

s. What percentage of the bulbs have lifetimes that lie within 1 standarddeviation to either side of the mean
Mathematics
1 answer:
Tcecarenko [31]3 years ago
8 0

Answer:

Step-by-step explanation:

p(\overline{X}-\sigma \leq X \leq \overline{X}+\sigma)\\\\=p(\dfrac{\overline{X}-\sigma -\overline{X} }{\sigma} \leq  Z \leq \dfrac{\overline{X}+\sigma -\overline{X} }{\sigma} )\\\\=p ( -1 \leq Z \leq 1)\\\\=2*(\ p (Z \leq 1)-0.5)\\\\=2*(0.8413-0.5)\\\\=0.6826\\\\\approx{68\%}

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Sarah has 25 coins that are dimes and nickels. Together they total $2.00. How many of each type does she have?
Ivanshal [37]

Answer:

15 dimes and 10 nickels

Step-by-step explanation:

15 dimes because 15 multiplied by 10 cents is $1.50

10 nickels because 10 multiplied by 5 cents is $0.50

15 x 0.10 = 1.50         10 x 0.50 = 0.50

0.50 + 1.50 = 2.00

8 0
3 years ago
Read 2 more answers
Sample Work Help Needed! Please answer these questions and show the steps used to solve them. NO DECIMAL ANSWERS (except on thre
anygoal [31]

1. Using the exponent rule (a^b)·(a^c) = a^(b+c) ...

\left(-2x^3y^4\right)\left(5x^9y^{-2}\right)=(-2)(5)\left(x^{(3+9)}y^{(4-2)}\right)\\\\=-10x^{12}y^{2}

Simplify. Write in Scientific Notation

2. You know that 256 = 2.56·100 = 2.56·10². After that, we use the same rule for exponents as above.

8 \left(32\times 10^{11}\right)=(8)(32)\times 10^{11}=256\times 10^{11}=2.56\times 10^{13}

3. The distributive property is useful for this.

(3x – 1)(5x + 4) = (3x)(5x + 4) – 1(5x + 4)

... = 15x² +12x – 5x –4

... = 15x² +7x -4

4. Look for factors of 8·(-3) = -24 that add to give 2, the x-coefficient.

-24 = -1×24 = -2×12 = -3×8 = -4×6

The last pair of factors adds to give 2. Now we can write

... (8x -4)(8x +6)/8 . . . . . where each of the instances of 8 is an instance of the coefficient of x² in the original expression. Factoring 4 from the first factor and 2 from the second factor gives

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8 0
3 years ago
What does A equal: 3(6a+12)=9
melisa1 [442]

Answer:

a = -3/2

Step-by-step explanation:

3(6a+12)=9

Divide each side by 3

3/3(6a+12)=9/3

6a+12 = 3

Subtract 12 from each side

6a+12-12 = 3-12

6a = -9

Divide by 6

6a/6 = -9/6

a = -3/2

5 0
2 years ago
Read 2 more answers
Madison is picking out some movies to rent, and she has narrowed down her selections to 7 foreign films, 3 horror films, 6 actio
Aleksandr [31]

{_{16}C_5}=\dfrac{16!}{5!11!}=\dfrac{12\cdot13\cdot14\cdot15\cdot16}{2\cdot3\cdot4\cdot5}=4368

8 0
3 years ago
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841 rounded to the nearest 10 and 100
LUCKY_DIMON [66]

Answer:

rounded to the nearest 10 is 840

rounded to the nearest 100 is 800

Step-by-step explanation:

6 0
3 years ago
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