Monday

July 28, 2014

July 28, 2014

Total # Posts: 17,552

**statisticsWere did i go wrong thank you**

mean = 97 correct difference and square of difference -14 196 -1 1 3 9 3 9 9 81 sum of squares = 296 variance = 296/5 = 59.2 square root of variance = standard deviation = 7.69

**whoops, order wrong**

then divide by n then take the square root

**statisticsWere did i go wrong thank you**

http://www.mathsisfun.com/data/standard-deviation-calculator.html

**statisticsWere did i go wrong thank you**

then take the square root, then divide by n

**statisticsWere did i go wrong thank you**

The differences SQUARED

**Physics**

u = 1540 cos 52 = 948 the whole time Vi = 1540 sin 52 = 1214 at start v = Vi - 9.8 t 0 = 1214 - 9.8 t t = 124 seconds to top so 2 t = 248 seconds in the air (part B) range = u * 2t = 234,871 meters or 235 km

**Statistics/I am confused**

difference from mean = 115-105 = 10 below mean variance = 25 so standard deviation = 5 so z = -10/5 = -2 it is two standard deviations below mean for z = 2 look up in normal table http://davidmlane.com/hyperstat/z_table.html probability = .0228

**algebra**

|+1 +0 | |-2 +3 +8 | |+0 -1 | |-3 +5 -1 | = | -2 +3 +8 | | +3 -5 +1 | so (-2,3), (3,-5), (8,1)

**geography**

Just some suggestions 1. Location maybe in Southern California on the west coast of USA. 2. Place What defines this place? Hollywood? Freeways? 3. Human interaction with environment You have to mention smog and the use of cars and air conditioning. You have to point out that t...

**math**

(y+6)^2 + (-6)^2 = 100 y^2 + 12 y + 36 + 36 = 100 y^2 + 12 y - 28 = 0 (y-2)(y+14) = 0 y = 2 or -14 y = 2 is on your list

**Math**

Note the tangent is perpendicular to the radius where it hits the circle.

**Math**

21/2 is rational but not integer and it is more than 5 and more than 2 so a square would solve the problem. put points at (21/2, 21/2) in quadrant 1 then its image (-21/2, 21/2) in quadrant 2 then (-21/2, -21/2) in quadrant 3 and (21/2,-21/2) in quadrant 4.

**Statistic**

5. 115 - 100 = 15 z score means how many standard deviations away from mean so 15/10 = 1.5 A+ :)

**Statistic**

http://easycalculation.com/statistics/standard-deviation.php

**Multiply write the result in scientific notation.**

(9*10^4)(8*10^6) = 72^10^10 = 7.2*10^11

**physics**

10 * 44 = 440 meters

**geometry**

volume = (1/2) (4/3) pi r^3 = (2/3)pi r^3 so 486 pi = (2/3) pi r^3 so r^3 = (3/2)(486) = 729 area of half of hemisphere = (1/2) 4 pi r^2 = 2 pi (729)^(2/3) = 162 pi

**physics**

a = F/m a = (2.36 cos 44.8 ) /.22

**algebra**

Evaluate 3p/q when p=2 and q=6. Answer:1 YES Use < > or = for __ to write a true sentence: 0.001 __ 0.0010 Answer:< Question 3 _______________ = ___________________ Evaluate -3/8 - 5/8. Answer:7 Question 4 ____________________ -8/8 = 1 __________________ Evaluate: 84 ...

**engineering mechanics**

Just look at the solved problems linked below. This problem may be the most common in all of algebra and beginning physics :) Remember and hour is 3600 seconds.

**math**

Equations have = signs

**trig**

(1 + tan^2A)(1 -sin^2A) but (1 - sin^2 A) = cos^2 A and (cos^2A/cos^2A + sin^2A/cos^2 A) = 1/cos^2 A so we have (1/cos^2 A)(cos^2 A) which is 1

**math**

tan theta = 9/175

**Math**

Nor do I. Have you mixed up two problems?

**math**

11 + 5 = 16

**Science**

Mass does not depend on gravitational constant anywhere. 5 kg is 5 kg b) m g = 5*9.81 N

**ENGLISH**

Pretty Calf says exactly why.

**math**

Find LCD 40 = 2*2*2*5 25 = 5*5 10 = 2*5 so 2*2*2*5*5 = 200 so 15/200 , 32/200 and 20/200 3/40 1/10 4/25 B

**precal help asap**

There are in fact an infinite number of solutions I would try each of the choices I have my calculator set on degrees so 2pi = 360 tan^2 (360/3 ) = 3 Yes that works tan 180 does not work tan -60 does not work tan 300 = nope so only A

**algebra/please help I have been wrong twice**

You are welcome.

**algebra/please help I have been wrong twice**

p(oil) = 1/40 p(gas) = 1/20 p(oil and gas) = 1/800 so (1/40)(395,000) = 9875 (1/20)(125,000) = 6250 (1/800)(520000) = 650 So I get 16,775 income - 25,000 expense = -8225 They expect to lose money I think.

**PRECAL MULTIPLE CHOICE**

sin A/a = sin B/b sin B = (b/a) sin A = 1.036 no solution (sin may not be greater than 1)

**math**

f' = -12 x^2 + 16 x + a f" = -24 x + 16 sheds water when when f" is negative holds waster when f" is positive f" is 0 when x = 2/3 sheds water when x < 2/3 holds water when X>2/3 so B

**math**

f(4) = 64 f(1) = 1 63/3 = 21 = average slope in interval f' = 3 x^2 = 21 x = +/- sqrt 7 in interval x = sqrt 7 = c so A

**Physics**

g is about 32 ft/s^2 in these obsolete units 61.8 miles/hr * 5280 ft/mi * 1 hr/3600seconds = 90.6 ft/s 7 * 32 = 224 ft/s^2 a = change in v/change in tim 224 = 90.6/t t = .4 seconds

**Science**

+2e

**Science**

By the way, remember transportation losses and expenditures including expense and losses of electrical cables particularly under sea.

**Science**

Actually I did not intend to write a PhD thesis before lunch. Post your attempt first please. Use the sources you have learned about (coal, oil, natural gas (fracked or otherwise) , nuc, hydro, wind, waves, solar panels etc )

**physics**

away of course in general for non-relativistic Doppler effect f heard = f emmitted (c+vr)/(c+vs) c = v of wave vr = v receiver (plus if toward source) vs = v source, (plus if source moving away from receiver) use your c of sound 78 = 80 (c+0)/(c+vs)

**calculus**

Horizontal speed constant forever = 80 cos 45 = u = 56.6 ft/s Initial vertical speed Vi = 80 sin 45 = 56.6 ft/s Now you did not give me the quadratic so I will have to solve it with physics v = Vi - g t where g = about 32 ft/s^2 in these obsolete units then h = Hi + Vi t - 16 ...

**English**

I think it could mean one of two things: 1. Instead of arguing about who would pay how much, I "simply" picked the bill up. 2. I "just" picked the bill up a minute ago.

**Math**

2/50 - 75/50 = -73/50

**technology**

work in = work out 10 * 100 = F * 20 F = 50 N

**Physics**

volume of man = 75 liters so density of man = 80 kg/75 L = 1.067 kg/L x(fat density ) + (1-x)(bone density) = 1.067 .9 x + 1.1 (1-x) = 1.067 1.1 - 1.067 = (1.1-.9)x x = .167 or 17%

**Algebra 1**

sorry, read reply wrong. You have it fine

**Algebra 1**

number or blacks = b number of whites = b+10 total - b +b+10 = 2 b+10 black first b/(2b+10) now we have b-1 blacks we have b+10 whites still total = 2b+9 b/(2b+10) * (b+10)/(2b+9) note - not 2b+10 in numerator

**trig**

rise = .1 run tan theta = .1 theta = 5 deg

**algebra**

36 possible outcomes if order matters If it is the sum that matters you have to figure a different probability for every sum for example there are 4 ways of getting a sum of 5 1+4 or 4+1 2+3 or 3+2 to get a sum of 6 though, there are 5 ways 1+5 or 5+1 2+4 or 4+2 3+3 On the fir...

**algebra**

I suspect they mean including 1 and 100 and not 2 through 99 so 100 numbers total so 5, 10, 15 ...... 100 are multiples How many? 10 * 2 = 20 20/100 = 1/5 so 1 - 1/5 = 4/5

**Trig**

current north speed = 3.2 sin 38=1.97 N current west speed = 3.2 cos 38 = 2.52 W Total North speed = 8.5+1.97 = 10.47 Total west speed = 2.52 tan theta = 2.52/10.47 theta = 13.53 degrees west of north or 47.47 degrees north of west Is the direction you are GOING (you are still...

**trig**

cos 35 = h/15

**Physics**

Yes, if the friction was less than the force required to accelerate the upper block, it would accelerate more slowly than the bottom one. In other words slip :)

**Physics**

You are welcome :)

**Physics**

F = - k x = -130 (.1) = -13 N if they do not slip m = 6.25 kg a = 13/6.25 = 2.08 m/s^2 force required to accelerate small block = 1.25 *2.08 = 2.6 N do we have that much? weight = m g = 1.25 * 9.81 so max friction = .3*1.25*9.81 = 3.68 N so no slip :)

**Math? Check Answers Please!!**

You are welcome :)

**Math? Check Answers Please!!**

1) yes 2)4^4 * 4^6 = 4^(4+6) = 4^10 3)4^(4+44) = 4^48 4) 3^(4-4) = 3^0 = 1 note ANYTHING^0 = 1 5) 3^-3 = 1/3^3 = 1/27 yes

**Physics**

2.05 2.04

**Physics**

initial momentum forward = (69.5+.47)(2.15) = 150.4 so 150.4 = 69.5 v + .470*16 in second part v ball = 2.15 + 16 = 18.15 m/s 150.4 = 69.5 v + .470*18.15

**Science**

Thanks for catching that !!!

**Science**

You have to add heat so endothermic 129 J per 2 mol 1 mol = 23 + 1 + 12 + 48 = 84 grams 2 mol = 168 grams we only have 18.5 grams so (18.5/168)129 = 14.2 Joules

**Physics**

change in x momentum = 2 * mass * x velocity = 2 * .275 * 4.5 sin 35 force on ball by wall = change in momentum /time = change in momentum/.008 wall on ball is -x so ball on wall is + x direction

**Math Homework: Check Answers**

You are welcome.

**Math Homework: Check Answers**

1. Suppose you earned 8t - 3 dollars on Monday and 6t + 5 dollars on Tuesday. What were you total earnings? Simplify your answer. A) 2t + 2 B) 2t - 8 C) 14t + 2 D) 14t - 8 Answer: A ------------------------------- 8t+6t= 14 t !!! so 14 t + 2 -------------------------------- 2....

**physics**

r w^2 = Ac = 6*10^5*9.81 w^2 = 58.9 * 10^5 /.02 = 29.4 *10^7 = 2.94 * 10^8 w = 1.72 * 10^4 = 17,200 radians/sec

**probability**

-->1 2 3 4 5 6 1 ----- * 2 ----* 3 --* 4 * 5 6 36 possible outcomes get 5 from four of them so p = 4/36 = 1/9 (1/9)180 = 20 times

**geometry**

Area of base = (1/2)(.25)(.25 sin 60) = .0271 m^2 .0271 * h = 7.5 h = 277

**physical science**

You are welcome :)

**physical science**

see below I got 94 %

**physical science**

100( power out ) /power in 100*3760/4000 = 94 %

**Geometry**

between 0 and 1 hour Ann went 3 miles per hour between 1 hour and 4 hours, Ann went 2 miles (5-3) so 2 miles /3 hours = .67 mph between 4 hours and 7 hours Ann went zero miles (5-5) so zero miles/hour (lunch break?) between 7 ours and 10 hours (3 hours) Ann went 5 miles (10-5)...

**ALGEBRA! URGENT. Check Answers!**

You are welcome.

**ALGEBRA! URGENT. Check Answers!**

yes

**ALGEBRA! URGENT. Check Answers!**

in #3 + 5x - 7x = NEGATIVE 2 x #4 negative 7

**math**

bottom = pi r^2 top = pi r^2 side = 2 pi r h

**Physics, am i right?**

If you have a whole bunch of resistors in parallel you can do 1/R = 1/R1+ 1/R2 + 1/R3 + 1/R4 .... Since the current has a choice which resistor to go through, you are adding CONDUCTIVITIES (inverse of resistance) C = C1+C2+C3 ... then in the end R = 1/C or you can do them cons...

**Physics, am i right?**

You are very welcome :)

**Physics, am i right?**

R = 10*20 /30 = 20/3 i = 9 /(20/3) = 27/20 = 1.35 Amps Yes !

**calculus**

(14x + 4)cos(7x^2 + 4x)dx,substitution u = 7x^2 + 4x. u = 7 x^2 + 4 x du = 14 x dx + 4 dx = (14x+4)dx so we have integral of cos u du which is - sin u + c - sin (7x^2+4x) + c

**calculus**

u = x3 + 5x2 + 18 then du = 3 x^2 dx + 10 x dx so in fact we have u du integrate u^2/2 + c so the hard part is squaring .5 (x^3 + 5 x^2 + 18)^2 + c

**histoy**

Life tenure is democratic NO ! Important people have special rights in a democracy NO People vote in a democracy YES Some slaves freed? What about the rest ? Not the question anyway. Some democracies had slaves (Athens, USA). They may not be proud of it.

**Physics**

R = 10*30 / (40) = 7.5 45/7.5 = 6 Amps

**Physics**

10 in PARALLEL with 30 1/R = 1/R1 + 1/R2 or R = R1 R2 /(R1+R2)

**Physics**

NO!!!

**algebra**

P(mean of A) if mean P(A) = .6 If we have six Apples and four Oranges in a box then P(A) = .6 when we draw one thing at random. If we have a whole bunch of boxes and on the average there are six apples in each then P(A) = .6 BUT The probability that we will draw that mean on a...

**algebra/Can you see if I am right**

Probability of the first one being a king is 4/52 probability of the first one being a face card = 12/52 the probability of the second one being a face card if the first was a king is 11/51 so if you mean probability of choosing a king, then a face card it is 4/52 * 11/51

**physics**

I have no idea.

**math**

add x to both sides x + y = a add -y to both sides x = a - y

**general chemistry**

Number of mols/liter

**math**

Instead of posting it again, read what you posted. It is incomplete. What is K and what does it have to do with the problem. We do not know the ratio of speeds for walking or taking the bus.

**Physics**

V = i R 20 = i (10) i = 2 amps so yes, b

**algebra/check my answer**

find probability that NONE are heads (1/2)^3 = 1/8 so we want 1 - 1/8 = 7/8 agree with you

**Calculus**

y^2 + 4 y = -8 x + 12 y^2 + 4 y + 4 = -8 x + 16 (y+2)^2 = -8 (x-2) vertex at (2,-2) opens left etc

**algebra**

You are welcome.

**algebra**

out of 13 men, 12 are bald? 12/13

**7th grade Math (polynomials)**

maybe: -8.5 x^3 + 0 x^2 + 1.1 x + 0

**algebra**

(-3)^2 -4(-3) + 3 9 + 12 + 3 24

**math**

7! = 7*6*5*4*3*2*1 = 5,040 agree

**maths**

10 *(10^x)^2 - 7 (10^x) = 26 let z = 10^x 10 z^2 - 7 z -26 = 0 ( z - 2)( 10 z + 13) = 0 10^x = 2 or 10^x = -1.3 if you log is base 10 log 10^x = x = log 2 but if x = log a then log a = log 2 so a = 2 similarly log 10^x = x = log (-1.3) but not allowed :)

**science (check!)**

agree, If the predator is not to run out of food, he needs a lot of prey per predator.

**Math, grade 10**

anyway a^2 + (17-a)^2 = 185 a^2 + 289 - 34 a + a^2 = 185 2 a^2 - 34 a + 104 = 0 a^2 -17 a + 52 = 0 (a- 13)(a-4) = 0 a = 4 or 13 so they are 4 and 13 and my initial thought was wrong

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