Monday
June 27, 2016

Posts by Reiny

Total # Posts: 35,087

math
distance away = √(7^2 + 3^2) = ... tanØ= 7/-5 = -1 , Ø = 135° in a direction of N 45° W
May 10, 2016

Geometry
let the other base be x (x+13) (11)/2 = 220 solve for x
May 10, 2016

Math
sides must be in the same ratio, thus the perimeter is in the same ratio ratio of sides = 15/5 = 3:1 perimeter of original = 38 so perimeter of new one = 3(38) = 114
May 10, 2016

probability
prob of getting it right = 1/4 prob of getting it wrong = 3/4 prob of getting 3 of 10 right = C(10,3) (1/4)^3 (3/4)^7 = 120(1/64)(2187/16384) = appr .25
May 10, 2016

Math
You must mean 60000 ml^3. 60,000 ml^3 of water = 60,000 cm^3 (the beauty of the metric system) you didn't state which of your data values are the height, I will assume it is the 50 cm so let the height be h cm Volume = 30(60)h cm^3 1800h = 60000 h = 100/3 cm or appr 33.3 cm
May 10, 2016

math
i = .065/12 = .0054166... 2500(1.0054166..)^n = 7500 , where n is the number of months 1.0054166..^n = 3 log both sides, and use log rules n log 1.0054166.. = log3 n = aprr 203.37 months = 16.95 years
May 10, 2016

Math
Nope, only 2 guesses left
May 10, 2016

Math
Every student of mathematics must know and memorize the quadratic equation formula: for ax^2 + bx + c = 0 x = (-b ± √(b^2 - 4ac) /(2a) for yours: a = 1 b = -7 c = 7 x = (7 ± √(49 - 4(1)(7))/(2 = (7 ± √21)/2 x = (7 + √21)/2 OR x = (7...
May 10, 2016

Riddle
She was all keyed-up for this one.
May 10, 2016

Math
Did you count 3 N's ?? I only see 2 of them so prob = 2/7
May 10, 2016

Maths
son's age --- x father's age -- 4x 5 years ago: son's age = x-5 father's age = 4x-5 x-5 + 4x-5 = 70 solve for x, plug into my definitions
May 10, 2016

math
Find (f o g)(-­5) = f(g(-5)) g(-5) = -4(-5) + 3 = 23 f(23) = -2(23) - 7 = -46-7 = -53
May 10, 2016

math
use the same steps I just showed in your post above.
May 10, 2016

math
f(f^-1(x)) = x by the very definition of (f o f­-1(x)) so (f o f­-1)(4) = 4
May 10, 2016

math
All of the tutors on here are volunteers and monitor this site only for a part of their day. Sometimes I don't go on here for days, as when I am traveling. Furthermore, most of us are experts in only our fields. e.g. I would never attempt to answer a question in chemistry...
May 10, 2016

Maths grade 12
Are you using the . in siny.cosy as a multiplication sign? If so, then siny = sinycosy cosy = 1 and cos^2 y + cosy = p 1+1 = p p = 2 Am I missing something here?? Looks too easy, did you have a typo?
May 10, 2016

Math
I agree with all your answers. For the second one, you included the base. That's fine, it said nothing about excluding it. For later questions of this type, if it asks for the "lateral surface area" of a cone, you would exclude the circular base.
May 10, 2016

math
There are 5 card which are 6 or higher so prob(2 of those) = (5/10)(4/9) = 2/9
May 9, 2016

Math
multiply each term by -3 15 + x = -84 x = -99
May 9, 2016

Geometry
Just plug in the values ... V = lwh 306 = (6)(6)(h) h = 306/36 = 8.5 very easy
May 9, 2016

math
I will assume that you meant: A(-4,6) and B(4,0) for the foci Let P(x,y) be any point on the hyperbola By the basic definition of a hyperbola: |PA - PB| = 2a, the distance between the two vertices √( (x+4)^2 + (y-6)^2 ) - √( ( x-4)^2 + y^2) = ±2a but (2,0) ...
May 9, 2016

Mathh
For a "cube" it is understood that all the sides are equal, so clearly V = (90)(90)(90) cm^3 = 729000 cm^3
May 9, 2016

Math (Trig) lowering powers
cos^4(3x)-sin^4(3x) = (cos^2 (3x) + sin^2 (3x)(cos^2 (3x ) - sin^2 (3x)) = (1)(cos (6x) = cos 6x) Besides using the difference of squares in the second line, I used: sin^2 Ø + cos^2 Ø = 1 , and cos 2Ø = cos^2 Ø - sin^2 Ø
May 9, 2016

geometry
Yes, 56.842... by Pythagoras which you must have rounded off to 57
May 9, 2016

raisethorpe
Here is how I taught this stuff 45 years ago. Draw a time line from time = 0 (now) to time = 5 On top of the line, at year 2, put in 2000 at year 5, put in 4000 below the line, at year 0 or at "now", put 1000 at year 3 , put in x quarterly rate = .15/4 = .0375 Now ...
May 9, 2016

Linear Equation
"...that all planes are the same planes. " this implies that all equations must be multiples of each other, but... the first and second equations have different normals , so they are not parallel Unless I am missing something here, this question is not possible
May 9, 2016

Pre Algebra
slope = rise/run so .... slope of Dixie hill = 60/100 = .6 slope of Bell hill = 50/100 = .5 Liberty ... = 20/100 = .2 which is the biggest number??
May 9, 2016

Msth
4y + 4 + 3y - 18 + 14 = -28 7y = -28 y = -4
May 9, 2016

coordinate geometry
let the point be P(x,y) slope AP = (y-3)/(x-1) slope BP = (y-1)/(x-3) (y-3)/(x-1) = 3(y-1)/(x-3) xy - 3y - 3x + 9 = 3xy -3y - 3x + 3 2xy = 6 xy = 3 Test for reasonableness : I know P(12, 1/4) lies on it slope AP = (1/4 - 3)/(12-1) = -1/4 slope BP = (1/4 - 1)/(12-3) = -1/12 and...
May 9, 2016

math
First of all I checked for the right-angle , and 10^2 + 9^2 = appr 13.5^2 Look at your diagram: Your surface area would consist of the 3 rectangles plus the two equal triangles. the height of the rectangles is 9 inches, Area of rectangles = 9x10 + 9x9 + 9x13.5 = 292.5 area of ...
May 9, 2016

Geometry
3x-7y=-10 5x-y=-6 ---> y = 5x+6 sub that into the first 3x - 7(5x+6) = -10 3x - 35x - 42 = -10 -32x = 32 x = -1 then y = 5(-1)+6 = 1 the ordered pair (-1,1) is the solution do the same thing for the second problem
May 8, 2016

Geometric series
Just use the sum formula for a GP sum(n) = a(r^n - 1)/(r-1) for ours: a = -1, r = 3 -1( 3^n - 1)/(3-1) = -3280 3^n - 1 = 6560 3^n = 6561 you could just play around with powers of 3 or you could use logs n log3 = log 6561 n = log6561/log3 = 8 check: sum(8) = -1(3^8 - 1)/(3-1...
May 8, 2016

math
C = 2πr dC/dt = 2π dr/dt = 2π(.5) cm/s = π cm/s
May 8, 2016

calculus
= [(2/3)(1/3)(1 + 3x)^(3/2)] from 0 to 1 =[(2/9)(1 + 3x)^(3/2)] from 0 to 1 = (2/9)(4^(3/2) - (2/9)(1^(3/2)) = (2/9)(8) - (2/9) = 14/9
May 8, 2016

calculus
2 ∫ 5/(3+2x) dx 0 = [ (5/2) ln(3 + 2x) ] from 0 to 2 = (5/2)( ln 7- ln 3) = (5/2) ln (7/3)
May 8, 2016

Algebra
notice that the z score for the given data is (.32 - .30)/.01 = 2 using the normal distribution , I get .0228 or 2.28% makes sense to me. "Explain why or why not" ????? Makes sense since we did the math correctly
May 8, 2016

Maths (Coordinate Geometry)
You must have meant: "... so that the line joining P to A(9,-5) is perpendicular to P joining B(4,5) Recall this property of a circle: If any point P on the circle is joined to the endpoint A and B of a diameter, the AP is perpendicular to BP Thus AB must be a diameter ...
May 8, 2016

math
given: a = 6 a + 13d = 171 6+13d = 171 13d = 165 d = 165/13 term16 = term14 + 2d = 171 + 330/16 = 2553/13 term 16 = a + 15d = 6 + 15(165/13) = 2553/13
May 8, 2016

math
"The 3rd term of an Arithmetic Progression is 10 more than the first term" ----> a+2d = a+10 2d=10 d = 5 "the 7th term is seven times the first term" --> a+6d = 7a 6d = 6a a= d = 5 sum of 8ht and 15th terms = a+7d + a + 14d = 2a + 21d = 10 + 105 = 115
May 8, 2016

mathematics-permutation and combination
If I give you only the solution, the whole point of this webpage would be futile. I assume you came here to learn and not just to receive answers. So please read this ..... Create a method by setting up a pattern starting with simple cases: First of all , to have boys directly...
May 8, 2016

math
hint: write the terms this way: 3(1) , 3(4), 3(9), 3(16), 3(25) .... What do you see ?
May 8, 2016

Maths
width --- w length --- l 2l + 2w = 240 l + w = 120 ---- l = 120-w ** new width = 1.2w new length = .9l 2(1.2w) + 2(.9l) = 240 2.4w + 1.8l = 240 24w + 18l = 2400 divide by 6 4w + 3l = 400 sub in ** 4w + 3(120-w) = 400 4w + 360 - 3w = 400 w = 40 then in ** , l = 80 the original ...
May 8, 2016

math
let the point be P(x,y) If A is (5,0) and B = (16/3,y), then AP = (5/4)BP 4 AP = 5 BP 4√( (x-5)^2 + (y-0)^2) = 5 (16/3 - x) 4√( (x-5)^2 + y^2 = 5(16/3-x) square both sides 16( (x-5)^2 + y^2) = 25(16/3 - x)^2 16(x-5)^2 + 16y^2 = 25(16/3 - x)^2 looks hyperbolic to me...
May 8, 2016

math
h = -4.9t^2 + vt + 100, where v is the initial velocity when t = 4, h = 0 0 = -4.9(4) + 4v + 100 4v = -80.4 v = -20.1 the stone was tossed with a velocity of 20.1 m downwards
May 8, 2016

Maths
Direct translation of English to Math: (1/4)x = (2/3)x - 10 12 times every term: 3x = 8x - 120 -5x = -120 x = 24 The number is 24 (there is only one number, how can you say, "find the numbers" ? )
May 8, 2016

Algebra 1
You can't
May 7, 2016

calculus help amigos
Just use your "closest distance from a given point to a line" formula D = | 5(3) + 5(-4) + 7 |/√(5^2 + 5^2)) = 2/√50 = 2/5√2 = 2/5√2 units or √2/5 after rationalizing. or , (the long and traditional way): you know the slope of the given ...
May 7, 2016

Math
c+m = 40 ** 4c + 2m = 108 or 2c + m = 54 *** subtract ** from *** c = 14 , then m = 26 we have 14 cars and 26 motorbikes
May 7, 2016

math
I will interpret "bearing of 230°" to mean -140° in standard trig notation Using vectors: vector RG = (4,0) + (0,-3) + (4cos-140°, 4sin-40°) = (4,-3) + (-3.0412, -2.57115) = (.9358, -5.5712) |RG| = √(.9358^2 + (-5.5712)^2) = appr 5.65 km ...
May 7, 2016

math
if r = 20 cm arc of halfcircle = (1/2)(40)π = 20π perimeter of halfcircle = 20π + 40 = appr 102.832 cm if r = 3 ft arc of halfcircle = (1/2)(6)π = 3π perimeter of halfcircle = 3π + 6 = appr 15.425 ft
May 7, 2016

math
Josh, your numerical answers are correct, except it is the smaller wheel that would have to make 127 rotations to the 38 rotations of the larger wheel.
May 7, 2016

math
Done above when you became Wesley http://www.jiskha.com/display.cgi?id=1462666186
May 7, 2016

differential calculus
No derivatives or Calculus needed here, it is a basic algebra problem. I assume they left at the same time, so they travelled the same time when they pass distance covered by Beth = 60t distance covered by Alving = 20t+40 that difference is 30 miles 20t + 40 - 60t = 30 -40t...
May 7, 2016

Math Help!!!
sin24°=CD/BC CD = BC sin 24° = 15,052.07464 sin 24° Calculator time
May 7, 2016

Math
d^2 = x^2 + (x+6)^2 = 10^2 x^2 + x^2 + 12x + 36-100=0 x^2 + 6x -32 = 0 completing the square: x^2 + 6x + 9 = 32+9 (x+3)^2 = 41 x + 3 = √41 , I ignored the negative answer x = √41-3 = appr 3.403 one side is 3.403 , the other is 9.403 check: 3.403^2 + 9.403^2 = 99....
May 6, 2016

math
larger or small ---- 2 from 4 colours ---- 4 from 3 ribbons --- 3 number of ways to choose a balloon = 2*4*3 = 24
May 6, 2016

Math
multiply the first by 4 4x-12y = 4 4x + 5y = 4 subtract them: -17u = 0 y = 0 back into the first: x - 0 = 1 x = 1
May 6, 2016

Algebra
amount = 64(1/2)^(t/10) , where t is in minutes, and amount is in g. sub in t = 20
May 6, 2016

math
What made you "sure" it was B or C ? Did you perform a long algebraic or synthetic division??
May 6, 2016

Math CHECK MY ANSWER
Without even reading the question, I would have ruled out your choice as the only one it could NOT be, since the probability of any even has to be a number between 0 and 1, and 12/5 > 1 There are 12 letters listed, 5 of them are vowels so prob(a vowel) = 5/12
May 6, 2016

maths
14 men dig 10 metres in 6 days 1 man digs 10/14 m in 6 days 12 men dig 10/14(12) m in 6 days, or 12 men dig 60/7 m in 6 days 12 men dig 1 metre in 6÷(60/7) day, or 12 men dig 1 metre in 7/10 days 12 men dig 15 metres in (7/10)(15) days 12 men dig 15 metres in 10.5 days
May 6, 2016

Math
make your sketch, to see a triangle with sides 5 and 7 and the contained angle of 108° by the cosine law: AC^2 = 5^2 + 7^2 - 2(5)(7)cos108 = 95.6311... AC = √95.6311.. = 9.778... (I stored that in memory) by sine law: sinØ/7 = sin108/9.778.. sinØ = ....
May 6, 2016

math
interest for first 40 days = 8500(40/365)(.06) = $55.89 total owing at that time =$ 8555.89 makes payment of $2000 Balance remaining = 6555.89 interest for next 70 days = 6555.89(70/365)(.06) = 75.44 total owing at that time = 6631.33 makes payment of $2000, leaving a balance ...
May 6, 2016

Geometry
number of triples from 10 = C(10,3) = 120 the triple of Rutgers, Miami, and Clemson is specifically one of those prob(your event) = 1/120
May 6, 2016

Math
almost, you are showing the division the wrong way 2 L = 2000 ml 2000 ml/14 glasses = 142 6/7 ml per glass that means 142 ml will be in each glass (the equal amount part of the question) with 6/7 of the divisor of 14 left over which would be 12 ml left over check: so each ...
May 6, 2016

math
So first you want to know how many pairs I can form from the 7 horses , then arranging the other 5 That would be C(7,2) or 21 for the first part - the remaining 5 horses can be arranged in 5! or 120 ways So there are 21(120) or 2520 ways to finish the race
May 6, 2016

math
games won by Lee --- 15 games won by ---- 2(15) + 3 = 33 total games = 48 prob(Tasha wins) = 33/48 = 11/16
May 5, 2016

Math
h^2 = 5^2 + 6^2 = 61 h = √61 = .....
May 5, 2016

Trigonomentry
Steve did this for earlier http://www.jiskha.com/display.cgi?id=1462459298
May 5, 2016

Algebra
Did you switch names? http://www.wolframalpha.com/input/?i=xy-x%2By%3D0
May 5, 2016

math
use your definitions fourth term = ar^3 = 9(-1/3)^3 = 9(-1/27) = -1/3 or simply list the first 4 terms to see the 4th term 9, -3, 1, -1/3, ...
May 5, 2016

Algebra
before you even start, did you notice the two equations have the same slope, but have different y-intercepts. Thus they will never meet, and therefore there can't be a solution. If you try it anyway .... first equation: y = 2x+3 sub in the second 2x-2 = 2x + 3 -2= 3 , ...
May 5, 2016

math- geometry
Correct me if I am wrong in the understanding of the question. Round table, we don't know its radius, I eventually let it be r Smaller circle lies on the table, the radius of the smaller table is 1/2 or .5 m The area outside the circle is shaded and you said the area of ...
May 5, 2016

math- geometry
You started well , but it collapsed on you in the second part. I would not have rounded off intermediate answer, only round off your final answer. I assume you used a calculator, get into the habit of using the memories of the calculator to store intermediate answers. for area...
May 5, 2016

math
-2 9 -1 4 0 -1 1 -6 2 -11 looks like we are dropping the y by 5 for each increase of 1 in the x y = -5x - 1 , ----> I noticed that (0,-1) was the y-intercept
May 5, 2016

Math
find all pairs of factors of 72 72 = 1 x 72 = 2 x 36 = 3 x 24 = .... etc count them up, but I would not count the duplicates such as .... 24 x 3 36 x 2 72 x 1
May 5, 2016

Math
let the other side be x case 1: x/3.7 = 1.618 x = = 5.9866 or 6.0 inches to the nearest tenth case 2: 3.7/x = 1.618 x = 3.7/1.618 = 2.286.. or appr 2.3 inches
May 5, 2016

math 21
What is your question? the graph looks like this http://www.wolframalpha.com/input/?i=xy-x%2By%3D0
May 5, 2016

math
a^5/a^3 = a^2 x^9/x^5 = x^4 you do the others by simply using the division rule of powers.
May 5, 2016

math
yes check it by taking 1.8% of it
May 5, 2016

math
.018x = 72 solve for x
May 5, 2016

MATH HELP PLZ!
looks like the same as this http://www.jiskha.com/display.cgi?id=1462291500
May 5, 2016

math
earning in first year --- x earining in 2nd year = 5.5x earning in 3rd year = 5.5^2 x earning in 4th year = 5.5^3 x x(1 + 5.5 + 5.5^2 + 5.5^3) = 29250 inside the bracket is a GP, but since there are only 4 times, we might as well just add them up x(203.125) = 29250 x = 144 so ...
May 5, 2016

math
neighbour's age --- x (4x+7)/3 - 9 = 20 times 3 4x+7 - 27 = 60 4x = 80 x=20 The neighbour is 20 years old check: times 4 --->80 add 7 ---->87 divide by 3 --> 29 subtract 9 ---> 20
May 5, 2016

Geography
20°N, 80°E ----> right smack in the middle of India 20°S, 80° E --> you better be in a boat
May 5, 2016

Math
Confusing wording: "he first pyramid has a height of 6 inches and a base area of 10 inches" since you tell us the volume is 20 inches^2 , the base are must be 10 inches^2 I also will assume that the base does not change volume of 1st pyramid = (1/3)(10)(6) = 20 ...
May 5, 2016

math
The first 3 are correct. You check by making sure you subbed correctly in the formula and performed the arithmetic correctly. For the last one about Lucia I have no idea since we can't see your diagram.
May 5, 2016

math
whole circumference = 12π so your arc is 105/360 or 7/24 of that
May 5, 2016

Algebra
amount of cheaper mix --- x kg amount of expensive mix -- 18-x solve for x and sub into my definitions 5x + 10(18-x) = 7(18)
May 5, 2016

Math ---HELP!!!!!
I got .1587, which matches 16% or D Did you take 1 - ...., since it asked for "above" ?
May 5, 2016

Math ---HELP!!!!!
I got .6538 , so yours is close enough
May 5, 2016

Math ---HELP!!!!!
according to the chart I am using, I ge 43.26 , so I agree with your choice
May 5, 2016

math
Billions and billions of them ... here are just two of them: (0,-3) , (75.2 , 147.4)
May 5, 2016

math
base --- b height = b+5 (1/2)(b)(b+5) = 45 b^2 + 5b = 90 b^2 + 5b - 90 = 0 b = (-5 ±√385)/2 = appr 7.311 or some negative base = 7.311 , height = 12.311 check area = (1/2)(7.311)(12.311) = 45.0028.. not bad, my answer is correct
May 5, 2016

Math
I pasted your original post, so I don't have to scroll up and down. I have inserted the corrections. If nothing is shown , then the question was correct 1. Simplify. 3x^2+ 5x-5x^2-4x+5-2 A.-8x^2-9x+3 B.2x^2+x+3 C.-2x^2-9x+3*** D.-2x^2+x+3 ****** 3x^2+ 5x-5x^2-4x+5-2 = -2x^...
May 5, 2016

Math
do you not have a calculator? just watch the order of operation, should be [2cos(45)] - [tan(45)/90.5] - 64
May 5, 2016

math
Just translate into Math using your definitions of an AP a+5d = 7 ** a+ 3d = 2(a+d) - 1 a + 3d = 2a + 2d - 1 -a + d = -1 *** add ** and *** 6d = 6 d = 1 back in ** a + 5=7 a = 2 the first term is 2 check: sequence is 2,3,4,5,6,7,8, ... Is the fourth term less than twice the ...
May 5, 2016

error in data - Trigonometry
error in data if B is in quad III, then cosB must be negative I will assume you meant: cos B = -12/13 make sketches of triangles in the two quadrants for sinA = 1/2, y = 1, r = 2 x^2 + 1^2 = 2^2 x = √3 so tanA = y/x = 1/√3 for cosB = -12/13 in III x = -12 , r = 13 ...
May 5, 2016

Math
I assumed you made a sketch. On mine, I labeled the position of Ms Hunt as H on top of the tall building, its base J For the shorter building, I labeled its top as P and its bottom as Q I drew a horizontal from H to meet QP extended at R All kinds of right-angled triangles! ...
May 5, 2016

Math
you will need the vertex of this parabola the x of the vertex is -b/2a = 192.1/32.4 = 5.929 so add 5.9 or appr 6 years to 1925 to get the year 1931
May 4, 2016

  1. Pages:
  2. <<Prev
  3. 1
  4. 2
  5. 3
  6. 4
  7. 5
  8. 6
  9. 7
  10. 8
  11. 9
  12. 10
  13. 11
  14. 12
  15. 13
  16. 14
  17. 15
  18. Next>>