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3 years ago

13

Solve for x: x - 15 = -30

2 answers:

OleMash [197]3 years ago

5 0

X= -15

add 15 to both sides

Mrac [35]3 years ago

4 0

Answer:

x = -15

Step-by-step explanation:

x - 15 = -30

add 15 to both sides

x = -15

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Set A of six numbers has a standard deviation of 3 and set B of four numbers has a standard deviation of 5. Both sets of numbers

Alenkinab [10]

Given:

$\sigma_A=3$

$n_A=6$

$\sigma_B=5$

$n_B=4$

$\overline{x}_A=\overline{x}_B$

To find:

The variance. of combined set.

Solution:

Formula for variance is

$\sigma^2=\dfrac{\sum (x_i-\overline{x})^2}{n}$ ...(i)

Using (i), we get

$\sigma_A^2=\dfrac{\sum (x_i-\overline{x}_A)^2}{n_A}$

$(3)^2=\dfrac{\sum (x_i-\overline{x}_A)^2}{6}$

$9=\dfrac{\sum (x_i-\overline{x}_A)^2}{6}$

$54=\sum (x_i-\overline{x}_A)^2$

Similarly,

$\sigma_B^2=\dfrac{\sum (x_i-\overline{x}_B)^2}{n_B}$

$(5)^2=\dfrac{\sum (x_i-\overline{x}_B)^2}{4}$

$25=\dfrac{\sum (x_i-\overline{x}_B)^2}{4}$

$100=\sum (x_i-\overline{x}_B)^2$

Now, after combining both sets, we get

$\sigma^2=\dfrac{\sum (x_i-\overline{x}_A)^2+\sum (x_i-\overline{x}_B)^2}{n_A+n_B}$

$\sigma^2=\dfrac{54+100}{6+4}$

$\sigma^2=\dfrac{154}{10}$

$\sigma^2=15.4$

Therefore, the variance of combined set is 15.4.

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2 years ago

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AveGali [126]

Answer:

Step-by-step explanation:

Volume of the pyramid :

$V=\dfrac{x^2*h}{3} =554.9\\\\x^2*h=554.9*3\\\\h=15.1\\\\x^2*15.1=554.9*3\\\\x^2=\dfrac{554.9*3}{15.1} \\\\x=\sqrt{\dfrac{1664,7}{15.1} } \\\\x=\sqrt{110,24503311258278145695364238411...} \\\\x=10,499763478887644993681148554978...\approx{10.50}$

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2 years ago

Sunny_sXe [5.5K]

Answer: A 13.4

Step-by-step

a^2 + b^2= c^2 4^2 + b^2 = 14^2 16+ b^2= 195 b^2= 180 b= square root of 180 b= 6 square root of 5 or 13.42

7 0

2 years ago

3. Sam and Tim each have savings accounts. Every month they each put in some of their

Setler [38]

Answer:

$y = 30x +50$ --- Sam

$y = 20x +80$ --- Tim

Step-by-step explanation:

Given

Sam Tim

х --- f(x) --------------- g(x)

1 --- 80 --------------- 100

2 --- 110 --------------- 120

3 --- 140 --------------- 140

4 --- 170 -------------- 160

Required

Determine the y value

y value implies the equation of the table

Calculating the equation of Sam

First, we need to take any corresponding values of x and y

$(x_1,y_1) = (1,80)$

$(x_2,y_2) = (4,170)$

Next, we calculate the slope (m)

$m = \frac{y_2 - y_1}{x_2 - x_1}$

$m = \frac{170 - 80}{4 - 1}$

$m = \frac{90}{3}$

$m = 30$

Next, we calculate the line equation using:

$y - y_1=m(x-x_1)$

$y - 80 = 30(x - 1)$

$y - 80 = 30x - 30$

Make y the subject

$y = 30x - 30 + 80$

$y = 30x +50$

Calculating the equation of Tim

First, we need to take any corresponding values of x and y

$(x_1,y_1) = (1,100)$

$(x_2,y_2) = (4,160)$

Next, we calculate the slope (m)

$m = \frac{y_2 - y_1}{x_2 - x_1}$

$m = \frac{160 - 100}{4 - 1}$

$m = \frac{60}{3}$

$m = 20$

Next, we calculate the line equation using:

$y - y_1=m(x-x_1)$

$y - 100 = 20(x - 1)$

$y - 100 = 20x - 20$

Make y the subject

$y = 20x - 20+100$

$y = 20x +80$

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2 years ago

Military radar and missile detection systems are designed to warn a country of enemy attacks. A reliability question deals with

Nadusha1986 [10]

Answer:

Step-by-step explanation:

Given that a particular detection system has a 0.83 probability of detecting a missile attack.

Also each system is independent of the other to detect missile attack.

a) the probability that a single detection system will detect an attack= $0.83$

b) the probability that at least one of the systems will detect the attack given two systems= 1-Prob no system detects

= $1-(1-0.83)(1-0.83)\\\\=1-0.0289\\=0.9711$

c) If three systems are installed, the probability that at least one of the systems will detect the attack

= 1- none of the three systems detect attack

$= (1-0.17^3)\\=1-0.004913\\=0.995087$

d) We find that probability of detecting is more if we increase the system form 1 to 2 and 2 to 3.

Hence for safety and defence purpose multiple detection system is recommended.

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3 years ago