Wednesday
April 23, 2014

Posts by MathMate


Total # Posts: 9,948

statistics check
SE² is given by: [ Σ(y-yBar)^2 - [Σ(x-xBar)(y-yBar)]²/Σ(x-xBar)² ] /(n-2) I get: Σ(y-yBar)²=258.1 Σ(x-xBar)(y-yBar) = -168.7 Σ(x-xBar)²=296.9 n=10 to get se²=20.28

math
A=P[(1+i)^n -1]/i => P=Ai/[(1+i)^n -1] =1000000*(0.08/12)/((1+0.08/12)^480-1) =286.45023 per month.

Please help me solve
See http://www.jiskha.com/display.cgi?id=1372073330

Please help me solve
Multiply the temperature difference by the calorimeter constant to get the energy in joules.

Phil103 Informal Logic
I think you would be more productive if you read Chapter six before you attempt these exercises. For example: ~p∨q reads as not p or q, with the "not" applying to p only.

Strength of materials
You have posted a number of questions without your input, and most of all, without the accompanying diagrams, nor the descriptions to replace the diagrams. If you believe that we can imagine what the loading is like, you are mistaken. I suggest you concentrate on one particula...

Physics (Stress & Strain)
Area 10.5cm²=10.5*10^(-4) m² Load = 5550 N Stress =load/area =5550/(10.5*10^-4) Pa =5285.714 kPa Strain: 1.1mm/1.9 m =1.1*10-3 m / 1.9m =0.000 579 (no units)

math
This is an exponential function of the form y=ae^x Substituting x,y values (20,45)into the equation, 20=160*e^(45k) take logs on both sides and solve for k k=-(1/45)ln(8) =-0.04621 So the mathematical model becomes: y(t)=y0*e^(-0.04621t) t=time in hours y0=initial mass y(t)=ma...

Physics
2 grams of hydrogen occupies 22.4 litres, so 18000kg=18000*1000 g will occupy 18000000/2*22.4 L =9000 m³ (at STP)

maths
See: http://www.jiskha.com/display.cgi?id=1371992237 If you do not agree with the response, please post and explain.

maths
The problem we have on hand is: Maximize |xy| subject to: f(x,y)=0 where f(x,y)=2y^2+43x^2y-6xy+5y+2x^2+48x-174.3 To solve the problem, we will solve for the extreme values of xy, and choose from the extreme values the largest value of |xy|. To do this, we would use Lagrange m...

physics
Use kinematic equation v^2-u^2=2as v=0 (at 0.8m above floor) u=unknown a=-9.81 s=0.8 u^2=√(2*9.81*0.8)=15.696 u=4 m/s approx.

business math
We do not know if it is simple or compound interest. Since compounding frequency is not mentioned, we assume it is simple interest. The simple interest formula: Future value = present value(1+ni) n=number of years, i=annual interest So 4,370.91 =PV(1+3*0.03) => PV=4,370.91/...

statistics
This is a binomial distribution of n=240 trials with probability of success p=0.17 and of failure q=1-0.17=0.83. Mean=np=40.8 variance = npq=33.864 Std dev = √(33.864)=5.82

math
Divide by two until the remainder is 0 or 1. The corresponding quotients will give the powers of 2 to make up 2000. 2000/2=1000 R0 1000/2=500 R0 500/2=250 R0 250/2=125 R0 125/2=62 R1 62/2=31 R0 31/2=15 R1 15/2=7 R1 7/2=3 R1 3/2=1 R1 So 2000 in binary notation is 11111010000 or...

maths
Assuming 74.2 cm of pressure refers to the mercury column. Under standard temperature and pressure (273.15°K, 100 kPa=760.06 mmHg), the gas constant is: 62.364 L mmHg K−1   mol−1 molecular mass of N2=2*14.0067=28.0134 So volume occupied ...

maths
The solution is given for AD. Are you able to calculate AD²?

maths
I assume the last sentence is "What is AD?" since AD2 does not mean much. Hints: Use cosine rule to find ∠A, in triangle ABC. A=arccos((20²+24²-22²)/(2*20*24)) =arccos(41/80) = 59° (approx.) Then Area of triangle ABC =(1/2)AB.AC.sin(A) =(1/2)*2...

phy
Do check your previous post for answers before reposting! See: http://www.jiskha.com/display.cgi?id=1371911866

Physics :)
you're welcome!

Physics
A=[5,-6.5] B=[-3.5,7] If A is perpendicular to C, then A.C=0, or C=[6.5k, 5k] (verify that A.C=0) If in addition, C.B=15, we have C.B=[6.5k,5k].[-3.5,7] =35k-22.75k =12.25k But C.B=15, therefore 12.25k=15, => k=15/12.25=60/49 Therefore C=[6.5k,5k] =[390/49, 300/49] Check my...

Physics
Ignore mass of balloon and basket. Consider 1 m^3 of hot air: mass, m = 0.93 kg net upward force, F =(1.29-0.93)=0.36 kg = 9.81*0.36 N =3.53 N acceleration = F/m = 3.53/0.93 m/s² = 3.8 m/s² Note: At this acceleration, air resistance is significant.

Maths
In the given case, since the given polynomial is of the fifth degree, you only have to try S=1,2,3,4 and up to 5. In fact: Let's factor the polynomial f(x)=n^5-17*n^3+16*n =(n-4)*(n-1)*n*(n+1)*(n+4) From this you will find the factors have the following properties: if n=0 ...

maths
Assume the equation has three roots a,b and c: then (x-a)(x-b)(x-c)=0 x³-(a+b+c)x²+(ab+bc+ca)x-abc=0 which means (a+b+c)=-3 (negative of coeff.of x²) (ab+bc+ca)=-7 (coeff. of x) Hence a²+b²+c² =(a+b+c)²-2(ab+bc+ca) =3²-2(-7) =9-(-14) =23

maths - incomplete
I'm afraid I do not make a lot of sense out of the the following definition: f(x2+1)1x√=x6x Kindly verify before and after posting your question.

Precal
5^(-t/2)=0.20 take log on both sides, (-t/2)log(5)=log(0.20) solve for t -t/2 = log(0.20)/log(5) t=-2log(0.20)/log(5)...isolate t =log(1/0.04)/log(5)...absorb -2 into log(0.2) =log(25)/log(5)... evaluate reciprocal =2... laws of logarithm, 25=5²

Math
The ordinary interest method is to calculate simple interest based on 360 days in a year. So interest=principal*(days/360)*rate 68.50=principal*(274/360)*6% therefore principal=68.50*(360/274)/0.06 =$1500

statistics
The answer should be a negative number as the numbers increase as x becomes smaller. The correlation coefficient lies between -0.2 and -0.3. Please post your equation for r again to see if it is interpreted correctly. Most of the time mistakes come from incorrect interpretatio...

statistics
What did you get using the given formulas 13.2 and 13.3?

math
Exact interest is based on a 365-day year. From June 30 to September 17, three months have passed. Both July and August have 31 days, while June has 30 days. So the duration of the loan is 30+31+31-3=89 days. Interest =Principal*(days/365)*0.10 =19000*(89/365)*0.10 =$463... do...

Algebra 2
Let y=kxz 98/3=k(2*7) k=98/3/14=7/3 Therefore y=(7/3)xz when x=7, z=3 then y=(7/3)*7*3=49

algebra - incomplete
I suspect you have missed out part of the question, such as: a) A∪B b) A∩B ... etc. Which is/are the "given set"?

Math Algebra 1A
I am not too sure what exactly your question is asking. If the time is elapsed since 1995, then you would subtract 1995 from the year in question. For example, 2004 is 9 years since 1995.

Physics
Assume a distance of d from the fulcrum. Take moments about the fulcrum: 350*2-540d=0 d=1.296 m

Physics
If I were to do the calculations, I would always work with stress, because ultimate stress is constant from problem to problem if the same material is used. It helps to spot errors, if any. Ultimate strength = 550 mPa. Stress under load = 64000/(7.6*10^-4) =84.2 mPa Now find t...

Physics
Required capacity of bar (in tension) =225kN*7 =1.575 MN Tensile strength = 231 MPa Area required =1.575 MN / 231 MPa =0.006818 m² =6818 mm² From πr²=6818 radius=√(6818/π) = 46.6 mm (or more)

Math
P²-0.037 = 0 P²=0.037 P=√0.037 Your calculator will give you the numerical value.

maths
A stimulating problem, combining probabilities with discrete mathematics. The question requires the probability of successively picking two balls of same colour be the same before and after adding 14 balls of a new colour. Initial situation: Assume there are n balls with k of ...

math - Tom Beth & Brad
Please do not use aliases, and do not repost within a short interval.

math
Let A = borrowed amount then A*(0.132)*2.5 years = 1320 A=1320/(0.132*2.5) =4000

Math (Trigonometry)
tan(θ)=1/4 => cos(θ)=4/√17, and sin(θ)=1/√17 Guess you can take it from here.

Calculus 2
Assume all measurements are in metres (since g is given as 9.8 m/s^2) The centre of gravity of the full tank is at 1.5/2=0.75 from the bottom. Work done is equal to the potential energy of the water at the spout (top) minus the potential of the full tank. Volume of tank, V=(&p...

math help
The probability is all the question wanted. If you have a more detailed question, kindly post. We do not generally follow all your previous posts.

math help
The probability of committing a type I error is the level of significance, α. See: http://www.cs.uni.edu/~campbell/stat/inf5.html

Algebra
Polynomials with all terms in even degree are even functions, and those with all odd degree terms are odd functions. For this purpose, a constant k can be considered as k*x^0, so it is even. A mix of even and odd degree terms is neithter odd nor even. Example: f(x)=x^6+x^2+4 i...

Physics
See your other post. Try to work with stress for comparison.

math
This has been posted many times, and answered more than once by different teachers. The solution to the system of algebraic equations are: (3,1),(1,3),(-2,4),(4,-2). The maximum value of |xy| is therefore 8.

math
The solution to the system of algebraic equations are: (3,1),(1,3),(-2,4),(4,-2). The maximum value of |xy| is therefore 8.

computer
It would be more helpful if you can indicate: 1. blank means black, white or blue screen? 2. What happened during the "booting" process, i.e. since the computer is turned on. Did you see any messages (whether you are able to decipher them or not). 3. Have you tried p...

math
This seems to be a programming challenge. While this can probably be worked out in mathematical terms, it is easily shown by exhaustive search that the 3-digit number is 199, where the minimum quotient is 199/19 =10.47 approximately.

diffirential calculus
Let the height be h (constant). First find radius in terms of V, volume. Volume, V = πr²h radius, r = √(V/(πh)) So the total surface area is obtained by substituting r in the following expression: A(total) =2πrh+2πr^2 =2π√(V/(πh))(√(V/(...

maths
obtained by adding the two vectors: (18,0)+(3cos(40),3sin(40)) =(18+3cos(40), 3sin(40)) =(x,y) The resultant speed R is obtained by |R|=sqrt(x²+y²)

Math
Let distance be D km, and the current be C km/h His speed is 8 km/h in still water. So his speed upstream is D/3.25=8-C and downstream, D/1.5=8+C Cross multiply each to get D = 3.25(8-C) D=1.5(8+C) Solve by comparison 1.5(8+C)=3.25(8-C) Isolate C 4.75C = 8(3.25-1.5) C=8*1.75/4...

maths - question incomplete
So far, ABC is just any triangle. The addition of the altitudes do not help. If it is further specified that BD intersects the segment AC at D, and CE intersects segment AB at E, and that BD and CE are equal, then it is possible to prove that triangles EBC and DCB are congruen...

statistics
A two-tailed test of a=0.05 is equivalent to two tests of a=0.05/2=0.025 for each for the upper and lower tails. So for |z|>1.96 has a=0.025 (two tailed) is equivalent to z>1.96 and z<-1.96. Ref: http://www.math.unb.ca/~knight/utility/NormTble.htm

math
Here m=7.50 / shirt b=set-up fee Since we know that 2450=7.5(300)+b => b=2450-7.50*300 =2450-2250 =200 So y=7.50x+200

Math
All good to me. For number 3, I am not sure if I understand the context of the question. I interpret it to mean what variable can adversely affect the accuracy of extrapolated data, in which case I choose independent variable. If an independent variable is chosen out of the ap...

maths
Distance travelled in one revolution = 2 × π × r where r is 3 cm. Distance travelled in 15 revolutions will be 15 time the above amount.

computer science
Read some of the articles on the subject, post a rough draft of your description, and we will be glad to critique your work. Some possible articles could be: http://en.wikipedia.org/wiki/Programming_language http://en.wikipedia.org/wiki/Category:Computer_languages

Math
FV=PV*(1+i)^n i=interest per period (year) expressed in fraction, =0.05 in this case. n=number of periods (year), = 12 in this case Your calculator can now be put to good use. Post for an answer check if necessary.

Math
We need to know how often interest is accrued. It is not always equal to the payment frequency. Some banks compound every 3 months, some six months, and some a year. For lack of information, we will assume that interest is compounded monthly, which simplifies the calculations....

algebra
Distance driven = 50 mph * (1/2) hour = 25 miles Distance to go = 100-25=75 miles.

Physics
acceleration =(v1-v0)/t =(34-10)/5.35 m/s² =4.486 m/s²

math
See http://www.jiskha.com/display.cgi?id=1371989906

maths
y2:x2=y1:x1 so y2=(y1/x1)*x2 =(15/9)*33

math
Height=Horiz. distance * tan(∠elev) =42*tan(36°)

mathematics
The way to proceed is: 1. plot the two points (3,-7) and (-9,21) on graph paper 2. join the two points with a straight line (using a straight-edge) 3. If the line passes through the origin, then the two ratios are in proportion.

Algebra 2 ..
(-16)^(1/4) =((-16)^(1/2))^(1/2) using rules of exponents =√√(-16) =√(4i) =√(2²i) =2√(i)

algebra
If you compare two graphs, which we don't see, you will need to describe or define the axes of the graphs. Does the x-axis represent the amount of gas consumed in gallons, and the y-axis represent the distance travelled? If that is the case, the rate of change represents t...

Programming
If you need debug help, please 1. specify the compiler/language 2. supply error messages you got when the programme was executed or compiled. 3. indicate if it is a compilation, execution or logical error. This one looks fishy: output "Enter student name or ", QUIT, ...

math
Choosing 3 out of 11 is given by: 11C3 =11!/[(11-3)!3!] =11*10*9/(1*2*3) =165

math trigonometry
See: http://www.jiskha.com/display.cgi?id=1371300101

st.paul
112,000,000,000

mATHS
Take away the legs of the 3 extra stools, which leaves us with 72-9=63 legs for equal number of stools and tables. Divide 63 by the total number of legs of one of one set (7 legs for 1 table and 1 stool), we have 63/7=9 sets. So he made 9 tables and 12 stools.

trig
Since (5,12,13) is a Pythagorean triplet, tan(θ)=5/12. Mathematically, we solve it by: Divide by the right hand side: (5/13)sin(θ)+(12/13)cos(θ)=1 Since (5/13)²+(12/13)²=1, we can put 5/13=sin(φ) 12/13=cos(φ) so sin(φ)sin(θ)+cos(&p...

maths
common ratio = (1458/2)^(8-2)= ±3 So the g.p.s are 2/3,2,6,18,54,162,486,1458 or -2/3,2,-6, ....1458

physics
Acceleration phase: initial velocity, v0 = 0 m/s final velocity, v1 = at = 8*20 = 160 m/s distance, S = ut+(1/2)at² = 0 + (1/2)8(20²) =(1/2)8(400)=1600 m Free fall phase: v0 = 160 m/s acceleration,a = -9.8 m/s² v0 = 160 m/s v1 = 0 a = g =-9.8 m/s² use v1&sup...

math
I guess I did not interpret the question correctly the first time around. "At least 4 blocks" means that the 2nd, 3rd, 4th streets (north-south) are not accessible. Similarly, the 2nd to the 12th avenues (east-west) are not accessible. So near the starting point ther...

math
All of them. Since there are 46x46 streets, there are 45x45 blocks. The dog has to run 4 blocks in a row in the horizontal direction, and 12 blocks in a row in the vertical direction, both of which are even numbers, it will never reach the food, in which direction it tries.

Calculus
f(x)=ax²+bx+c f'(x)=2ax+b f"(x)=2a f"(2)=3 => 2a=3 => a=3/2 f'(2)=2 => 2a(2)+b=2 => 3(2)+b=2 => b=-4 f(2)=6 => a(2)²+b(2)+c=6 => 4a+2b+c=6 => 6-8+c=6 => c=8 Therefore f(x)=(3/2)x²-4x+8 Using this final definition of f...

maths
Does an operation between two members of a group give you a unique value or multiple values?

math
When a problem requires "at least one", it is often easier to find the probability of getting none and subtracting the probability from 1 (complement). Here, probability of not getting a king at a draw is 48/52, or 12/13. Probability of getting no king at 4 consecuti...

Calculus
f(x)=x+4/x f'(x)=1-4/x^2 f'(2)=1-1=0 Equation of tangent line: y=0(x-2)+4, or y=4

Geometru
A heptagon has 7 sides. The sum of exterior angles is 360. The six given angles have exterior angles equal to: 60,30,45,10,90 and 55 for a total of 290. The remaining exterior angle is therefore 360-290=70°. The largest exterior angle is 90°.

algebra
For √, type in & r a d i c ; but without the intervening spaces. I will solve the first one: Use the FOIL rule (2√5-√28)(√28+4√5) =(2√5-2√7)(2√7+4√5) =4(√5-√7)(√7+2√5) =4(10-7-√5√7) =12-4...

math check
Sorry, the second one is P(z<1.51), which makes 0.9354 the correct answer.

math check
Four decimal places for 0.409 should be 0.4090. The second one is correct.

math
These two lines are parallel and distinct, hence there are no solutions. Show that this is the case by dividing the first one by two to get 5x+5y=515 Since both equations have 5x+5y on the left, and different values on the right, it shows that the two lines are parallel and di...

math
What do you think, and why?

math
P=principal = $3000 i=interest=0.06 n=number of 6-month periods FV=future value =P(1+i/2)^(n)

ssm
acceleration = v²/r

math
The probability of a red pen on the first draw is 4/18. For the second draw, there are 3 red pens left out of 17 pens total. The probability of both happening is obtained by multiplying the two probabilities: P(RR)=(4/18)*(3/17)=2/51

math
There are 2^10 possible subsets, including Φ, the null set. Not sure what you mean by sum of the elements, do you mean the sum of the cardinalities of the 1024 subsets, or do you mean the sum of the numbers of each subset? In the case of the latter, the distinct sums would...

math problem
Assume that the "grid" means "grid of squares" is the collection of all the squares, then we consider one square: The "safe" area for the centre of the coin is a square of 1/2"x1/2" out of a total of 1.5"x1.5". Probability is t...

math
Rewrite the word as: "ceeeffitv" we see that it is a 9 letter word in which the letters e and f repeat 3 and 2 times respectively. The number of permutations is therefore 9!/(3!2!1!1!1!1!) =30240

math
Since "education" can be written as "acdeinotu" a nine letter word without repetition, the number of permutations is 9! = 362880

computer
There are many free C/C++ compilers available. Notable ones could be Microsoft's Visual Express C++, Dev-C, Borland C/C++ compilers. Cnet has a whole section for that purpose. Note that some of the compilers listed at the Cnet site are try and buy. Here are some links: htt...

Probability
P(odd)=0.75 P(even)=0.25 P(3)=0.75/3=1/4 P(6)=0.25/3=1/12 Since 3 and 6 are mutually exclusive, P(3∪6)=P(3)+P(6)=1/4 + 1/12 = 1/3

Geometry
The radius is the distance between the centre and the given point, which is r=sqrt(15^2+4^2)=sqrt(241) The circle with centre (2,-5) is (x-2)^2+(y-(-5))^2=r^2 There is only one choice that fits these criteria.

Number Theory
Yes, it works! If we solve a,b,c in terms of d, we get, a=-(d+36)/6, b=d+11, c=-(11d-24)/6 from which we can define f(x)=x^4 -(d+36)x^3/6 +(d+11)x^2 -(11d-24)x/6 +d and based on this, f(1)=10 f(2)=20 f(3)=30 f(12)+f(-8)-19000 =-608(d+36)/3 +208(d+11)+2d+2(24-11*d)/3 +5832 =840

Pages: <<Prev | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | Next>>

Search
Members