Monday
September 26, 2016

Posts by Reiny

Total # Posts: 36,011

Maths
looks quite simple, draw your Venn diagram, label the intersecting circles sw, s and f place 5 in the intersection of the 3 circles. Now look at the intersection of th sandwich and fruit, it says 7 but you already placed 5 into part of that region, so that leaves 2 for the ...
September 20, 2016

Maths Profit and Loss
solve for x, the production cost (1.06)(1.08)(1.1)x = 14741
September 20, 2016

Maths Congruence
It has to be the contained angle
September 20, 2016

math
rationals and integers
September 20, 2016

maths
10 men to build a 1 house in 6 months 10 men to build a 1/6 house in 1 months 10 men to build a 4/6 house in 4 months 1 man to build a 4/60 house in 4 months 60/4 men can build 1 house in 4 months 15 men can build 1 house in 4 months or more simply it takes 60 man-months to ...
September 20, 2016

Math
a = 5.4 v = 5.4t + c but v = 0 when t = 0 , so c = 0 v = 5.4t s = 2.7t^2 + k but s = 0, when t = 0 , so k=0 2.7t^2 = 145 t^2 = 145/2.7 t = ....
September 20, 2016

maths
NO first of all you are using x incorrectly (in the third last line x = 8,2584, and in the last line x = 41292, which is a contradiction) furthermore, we place a comma after groups of 3 digits for easier reading, not groups of 4 digits. furthermore #2, if the height is 6 cm, ...
September 20, 2016

algebra 1
find √7 and √3 on your calculator, change -7/4 to a decimal Now you should be able to tell their relative size
September 20, 2016

Math
to solve: 2x+c = 8-2x-x^2 x^2 + 4x + c-8 = 0 to have y = 2x+c to be a tangent, there can be only one real root of the quadratic so b^2 - 4ac = 0 16 - 4(1)(c-8) = 0 16 - 4c + 32 = 0 4c = 48 c = 48/4 = 12 check with Wolfram: http://www.wolframalpha.com/input/?i=y%3D2x%2B12,+y%...
September 20, 2016

Algebra
jorges ---- x years brother ---- 3x - 4 solve x + 3x-4 = 24 and sub back into my definitions.
September 20, 2016

Math
both are good examples
September 20, 2016

Math
what is .25(40) ?
September 20, 2016

correction - Math
actually I misread the question, Now I see that 12x = 48 x = 4 so we have 48 soccer balls and 60 baseballs (even easier than before)
September 20, 2016

Math
soccer balls --- 12x baseballs ------ 15x solve 12x+15x=48 x = 16/9 soccer balls ---- 12(16/9) = 64/3 ???? bogus question! both soccer balls and baseballs must be whole numbers.
September 20, 2016

Math
Since the ball is returned, these are independent events prob(not white) = 12/17 we want this 4 times in a row, so prob(your event) = (12/17)^4
September 20, 2016

maths
Did you sketch your Venn diagram? The missing part is the intersection of all 3, label it x Now look at the intersection of A and C, it must be 34. But you already have x accounted for in the intersection of all 3. So label the part in A and C, but not B as 34-x 36 study A and...
September 20, 2016

Math
It takes 1 team 5 minutes to clean 200 yards It takes 2 teams 5 minutes to clean 400 yards (assuming they don't get in each other's way) 1760/400 = 22/5 It takes 2 teams 5(22/5) minutes to clean 1760 yards <b<It takes 2 teams 22 minutes to clean 1 mile (DonHo'...
September 20, 2016

Math
What she is referring to is this: 337 = 300 + 30 + 7 so the value of the 3 in the tens place is 1/10 the value of the 3 in the hundreds place
September 19, 2016

Math
what does x4x mean? did you mean x^(4x) ?
September 19, 2016

Math 6th grade
numbers which when divided by 4 leave 3: 7 11 15 19 23 27 31 35 39 43 ... numbers which when divided by 5 leave 3: 8 13 18 23 28 33 38 43 48 ... numbers which when divided by 6 leave 1: 7 13 19 25 31 37 43 ... ahh, 43 is in all 3 lists, so ....
September 19, 2016

math
P = I^2 R plug in your given 40 = I^2 (3) 40/3 = I^2 I = √(40/3) = ...
September 19, 2016

Math
20 hundredths = 20(.01) = .2 2 thousandths = 2(.001) = .002 What are you going to tell Janice ?
September 19, 2016

algebra
h = 15j j = h/15
September 19, 2016

Math
C = 560 + 40x inverse: interchange the variables x = 560 + 40C C = (x -560)/40 = g^1(C)
September 19, 2016

Math
4(log(x)+5)=6 log x + 5 = 6/4 = 1.5 log x = -3.5 x = 10^(-3/5) = .... I get x = appr .000316
September 19, 2016

Math
93=12(2)^p 2^p = 93/12 = 31/4 take logs log 2^p = log (31/4) p log2 = log31 - log4 p = (log 31 - log 4)/log 2 = you push the buttons.
September 19, 2016

Math
blue cars --- x red cars ---- 2x yellows ----- (1/3)2x = 2x/3 x+2x+2x/3 = 33 times 3 3x+6x+2x=99 take over
September 19, 2016

Math
prob(white, then green) = (7/50)(4/49) = ...
September 19, 2016

Algebra
Wouldn't the temperature be between 14 and 22 ? so 14 ≤ T ≤ 22 you were on the right track with |T - 18| but you should have said: |T - 18| ≤ 4 then T-18 ≤ 4 and -T + 18 ≤ 4 T ≤ 22 and -T ≤ -14 ----> T ≥ 14 the connective...
September 19, 2016

Algebra
I would double the first and get: 4x + 6y = 8 5x + 6y = 7 subtract them: x = -1 sub back into one of the originals to get y
September 19, 2016

Algebra
John's error, after multiplying by 3 , should be 15x + 12y = -42 , John had +42
September 19, 2016

Math
"the hundred digit is greater than 7" ---> 8XX or 9XX "the tens is one more than the hundreds digit" ---> 89X "the ones digit is less than 2" --- 890 or 891 "If my clothes are like this" ???????
September 19, 2016

Math
If t represents the hours she babysits, Charge = 8t + 2.50 that is, your equation would be 8t + 2.50 = 30.50 I have not clue why Smiley is multiplying the hourly fee by the cost of the bus ride. Smiley's reply is gibberish.
September 19, 2016

Physics needed - maths help me
need physics properties
September 19, 2016

Math
Surely you meant: b(t) = 50t/(t+1) or else the t's would just cancel b(1) = 50(1)/(1+1) = 51/2 or 25.5 b(2) = 50(2)/(2+1) = 100/3 = ... b(5) = 50(5)/(5+1) = 250/6 = .. etc
September 19, 2016

Maths
breath or width ---- x m length ------------- x+5 m given: x(x+5) = 84 x^2 + 5x - 84 = 0 (x -7)(x + 12) = 0 x = 7 or x is a negative width is 7, length is 12, so perimeter is .... ?
September 19, 2016

math
Oh my goodness! Steve showed you that 1 textbook weighs 1 kg so how much will 5 textbooks weigh ?
September 19, 2016

Math
solve for x (2/5)x = 80 (If she finished 3/5 of the book, then 2/5 remain to be read)
September 19, 2016

Math
I don't have that function on mine, so I have to actually think it through and do the math prob(a four) = 1/4 , prob(not four) = 3/4 at most 6 fours means: 0 four, 1 four, 2 fours, 3 fours, 4 fours, 5 fours, 6 fours. prob(your event) = C(22,0)(3/4)^22 + C(22,1)(1/4) (3/4)^...
September 18, 2016

math
easily done with a sketch across y = 3 (0,0) ---> (0,6) across the x-axis (0,6) ---> (0, -6) (remember that the equation of the x-axis is y = 0
September 18, 2016

Math
hour hand: 8:00 am to 11:30 am is 3.5 hours. on the face of a standard clock this is 3.5/12 or 7/24 of a rotation, thus 105° or 7π/12 radians minute hand from 8:00 am to 11:30 am the minute hand will have made 3.5 rotations or gone through 1260° or 7π radians
September 18, 2016

Algebra
can't get any easier than this one. add them to find X then subtract them to get y
September 18, 2016

math
24=ax+4y-10 34 - ax = 4y y = (34-ax)/4 or 17/2 - ax/4 , looks like B
September 18, 2016

math
A=1/2h(b1+b2) 2A = hb1 + hb2 2A - hb2 = hb1 b1 = (2A - hb2)/h
September 18, 2016

Calculus 2
If N is the number of bacteria dN/dt = 20e^.8t N = 25 e^.8t + 50 when N = 700 700 = 25 e^.8t + 50 e^.8t = 26 take ln of both sides .8t = ln 26 t = appr 4.07 check: if t = 4.07 N = 25 e^.8(4.07) + 50 = 698.6 , not bad
September 18, 2016

math
so the area is x^2 and the perimeter is 4x area = (1/2)perimeter x^2 = 2x x^2 - 2x = 0 x(x-2) = 0 x = 2 or x = 0 , the latter makes no sense
September 18, 2016

math
Your question did not make sense the first time you posted it, that is why nobody has answered it. Are we supposed to see some kind of square? Does the x "in the square" represent the area or the length of the side? Awaiting your clarification so I can answer your ...
September 18, 2016

Math
All kinds of problems with this question. It is invalid to compare "interest paid" when you don't have the same focal dates. Are there monthly payments? I sure hope you weren't thinking of using simple interest. Since the interest rates are the same, the ...
September 18, 2016

Math
#1 y-5/3 =1 y = 1 + 5/3 = 8/3 , none of the given choices if you meant: (y-5)/3 =1 , which changes your question, y - 5 = 3 y = 8 #2 6x + 29 =5 6x = -24 x = -4 , choice A
September 18, 2016

math
To handle this type of equation you should be familiar with the steps to solve basic equations. K=3gy/(5f) multiply both sides by 5f 5f*K=3gy/(5f)*5f 5fk = 3gy divide both sides by 3y 5fk/(3y) = 3gy/(3y) 5fk/(3y) = g as shown above
September 18, 2016

math
I have a hunch you meant: K=3gy/(5f) based on that hunch .... 5fk = 3gy g = 5fk/(3y) those brackets are critical.
September 18, 2016

Math
"1 square mile wide and 1 square mile wide" makes no sense, there are no such units Does he have a field 1 mile by 1 mile ? make a sketch of a square 1 by 1 Divide the sides into 3 equal length and draw the dividing lines. You should have an X and O like game grid ...
September 18, 2016

math
All you have now three times in a row is to state an equation. What about it? Are you solving for one of the variables? Which one? Ms Sue already pointed this out to you when you were Carlos, but you stubbornly repeat it the same way. You did not ask a question!
September 18, 2016

Math
correct
September 18, 2016

Math
interest for 3 months = 20500(.043)(1/4) = 220.375 amount owing at that time = 20720.375 after payment of 7100, amount owing = $13,620.375 interest on the next 5 months = 244.03 debt at the end of that time = $13,864.41 after the 6900 payment, balance at the end of 8 months...
September 18, 2016

Equivalent Payments
done, see your later post of this
September 18, 2016

math
fee for Great Gym = 19.5m + 59 fee for wacky = 9.5m + 149 so you want 19.5m + 59 = 9.5m + 149 10m = 90 m = 9 it would take 9 months, cost = 19.5(9) + 59 = $234.50
September 18, 2016

Math
Look at Damon's correct solution to the one above this. I did not read the question carefully enough and proved that the sum of any 3 consecutive numbers is a multiple of 3. btw, that is also true for any 3 consecutive even numbers.
September 18, 2016

Math
any three consecutive numbers: x , x+1, x+2 their sum = x + x+1 + x+2 = 3x + 3 = 3(x+1) since it contains a factor of 3, it must be a multiple of 3
September 18, 2016

Math
According to your wording, (x^3 + 1) ÷ 1/x^3 which is (x^3 + 1)(x^3) = x^3(x+1)(x^2 - x + 1) , using the factoring of cubes principle
September 18, 2016

Math
With 4 coins, more heads than tails ---> 3H1T or 4H prob 3 of 4 heads = C(4,3)(1/2)^3 (1/2) = 4(1/8)(1/2) = 1/4 prob 4 out of 4 heads = (1/2)^4 = 1/16 prob(your event) = 1/4 + 1/16 = 5/16 aside: prob(no heads) = (1/2)^4 = 1/16 prob(1 head) = C(4,1)(1/2) (1/2)^3 = 1/4 prob(2...
September 18, 2016

Maths
Same question here, just the numbers are different, so change them to yours. go for it! http://www.jiskha.com/display.cgi?id=1474104642
September 18, 2016

MATHS
1(1.055)^n = 2 use logs n log 1.055 = log 2 n = log2/log1.055 = appr 12.9 years In the "olden days" we used something called the rule of 72 rate x time = 72 so here time = 72/5.5 = 13.09 , not bad
September 18, 2016

Maths
.7x = 77 x = 77/.7 = ...
September 18, 2016

calculus
Have you learned about Newton's Law of Cooling?
September 17, 2016

Geometry
Let M be (x,y) Make a sketch , draw two right-angled triangles, with hypotenuse AM = 3 and hypotenuse MB = 2 then use similar triangle ratios. for the x: (x-0)/20-x) = 3/2 2x = 60-3x 5x = 60 x = 12 for the y: (15-y)/(y-0) = 3/2 3y = 30 - 2y 5y = 30 y = 6 M is (12,6) or: the x ...
September 17, 2016

maths need help
Small codicil: The diameter is 40 m , not the radius
September 17, 2016

maths need help
I am puzzled by: There is a road of width 1 m starting from 1 m away of its end point.
September 17, 2016

Maths
you must have meant: If (x+3) varies directly as y then, x+3 = ky when x=3, y=12, so 6 = 12k k = 6/12 = 1/2 then x+3 = (1/2)y or 2x + 6 = y when "you" = 8 2x+6=8 2x=2 x = 1
September 17, 2016

Algebra
cost of 1 fillup = 16(2.11) = $33.76 monthly cost = 2(33.76) = $67.52 monthly allowance = 4(25) = $100 left over = 100 - 67.52 = $32.48 your answer is right
September 17, 2016

Trigonometry
In each of your problems the linear equation can be easily expressed in terms of y. Then sub that into the other equation I will do #2 from x-y = -3 y = x+3 subbing into the other: x^2 - x - (x+3) = 0 x^2 - 2x - 3 = 0 (x-3)(x+1) = 0 x = 3 or x = -1 if x = 3, y = 3+3 = 6 if x...
September 17, 2016

Algebra
any line parallel to the y axis has the form x = ?? look at the given point, what is the value of x ?
September 17, 2016

Maths
smaller part --- x larger part ---- 8 - x 7x^2 > 2(8-x)^2 by 13 7x^2 = 2(8-x)^2 + 13 7x^2 = 128 - 32x + 2x^2 + 13 5x^2 + 32x - 141 = 0 (x - 3)(5x + 47) = 0 x = 3 or x = -47/5 the two parts are either 3 and 5 or they are -47/5 and 87/5
September 17, 2016

Math
Tough question! roots are: x = ( -k-2 ± √(k+2)^2 - 4(k)(-3) )/2k = ( -k-2 ±√(k^2 + 4k + 4 + 12k))/2k it said: both x's are positive, so ( -k-2 + √(k^2 + 4k + 4 + 12k))/2k > 0 assuming we started with a positive x^2 term, so k > 0 -k-2...
September 17, 2016

math
John --- x Mary --- 2x Susan -- 2x x+2x+2x=150 solve for x, sub back into my definitions Just noticed that Ms Sue already did this for you.(Related Questions below) Always check back before reposting the same problem.
September 17, 2016

Maths
Both Steve and I answered this for you. What part of the answer did you not like ?
September 17, 2016

miss reiny correct-done
Ok, revising my difference calculations 1 3 2 6 3 1 11 5 2 1 19 8 3 1 31 12 4 1 48 17 5 1 ahhh, so the third difference is constant, so we have a cubic let the term = an^3 + bn^2 + cn + d when n = 1: 1 = a + b + c + d when n = 2 3 = 8a + 4b + 2c + d when n = 3 6 = 27a + 9b + ...
September 17, 2016

math
you have to know the rules of logs I will use: log (xy) = log x + log y log(x/y) = log x - log y log (x^a) = a log x Log72/75-log50/48+2log25/24 = log [ (72/75) ÷ (50/48) (25/24)^2 ] = log [ (72/75(48/50)(625/576) ] = log [1] = 0
September 17, 2016

arithemetic progression too hard help plz
* = 1st difference , ** = 2nd difference, *** = 3rd difference # * ** *** 1 3 2 6 3 1 11 5 2 1 31 20 15 13 48 17 -3 -18 You labeled you subject "arithmetic progression", so I expected a linear relationship. The first, second and third differences are NOT constants, ...
September 17, 2016

Math
let's place the smallest numbers in the most significant decimal places, so .01378 assuming we can use each digit only once.
September 17, 2016

Math
yes I boils down to simply showing that 9:6 ≠ 4:3
September 17, 2016

Math
when comparing ratios, it is often a good idea to have the parts represented by the same number. teacher: yellow : blue = 9 : 6 Gina: yellow : blue = 4 : 3 = 8 : 6 So, what do you think?
September 17, 2016

Math
let the parts be 2x, 3x, and 5x 2x + 3x + 5x = 5000 solve for x, sub back into my definitions
September 17, 2016

Math
1 : 5 = 8 : 40 If 1 ticket costs $5, how much will 8 tickets cost?
September 17, 2016

Math
well, if Pablo gets 1 free minute for every 5 paid, then he would get 8 free minutes for every 40 paid, Sam is getting only 25 paid minutes for every 8 free ones
September 17, 2016

math
new fraction = 13/15 change = 13/15 - 7/9 = .. if your answer is positive, the value of the fraction increased, if the result is negative, the function decreased. Try it with another fraction. What do you think the question is trying to show?
September 17, 2016

MATH
original loan: payment -- p i = .132/12 = .011 n = 288 PV = 21000 p( 1 - 1.011^-288)/.011 = 210000 I got p = $2413.34 balance after 68th payment = 210000(1.011^87) - 2413.34(1.011^87 - 1)/.011 = $195,059.83 new payment - 2413.3-500 = 1913.34 new i = .072/12 = .006 PV = 195059....
September 17, 2016

Maths
So we only have 8 digits to choose from for our leading digit, then 9 digits for each of the remaining spots number of three digit numbers with no 5 = 8x9x9 = 648
September 17, 2016

algebra
13 + [26 ÷ (−6 + 4 * 1)] = 13 + [26 ÷ (-2)] = 13 + [-13] = 0 Proof: http://www.wolframalpha.com/input/?i=13+%2B+((26+%C3%B7+(%E2%88%926+%2B+4+*+1))
September 16, 2016

geometry
Of course I am not just going to give you the answer. You have an isosceles triangle with a base of 12 and equal sides of 10 So sketch in the altitude, and you will have a right-angled triangle with base of 6, hypotenuse of 10 and the missing height Use Pythagoras to find that...
September 16, 2016

Math
We "solve" equations, but you don't have an equation. I will assume you have: x^2 + 3x + 1/4 = 0 yes, I would also multiply by 4 to get 4x^2 + 12x + 1 = 0 Unfortunately , it does not factor, so you will have to use the quadratic formula to solve it, or you can ...
September 16, 2016

math
LS = Log384/5+log81/32+3log5/3-log9 = Log384/5+log81/32+log5^3/3^3-log9 = log( (384/5)(81/32)(125/27)/9 ) = log(100) = 2 = RS
September 16, 2016

math
Log56/63-log100/108-log72/75 = log( (56/63)÷(100/108) ÷ (72/75) ) = log( (56/63)(108/100)(75/72) ) = log(1) = 0
September 16, 2016

Algebra homework
sketch a quarter circle with an outer radius of 16 and an inner radius of 4 So the area not wiped has to be subtracted form the area of the whole quarter circle, so ... find the area of 1/4 circle with radius 16 find the area of 1/4 circle with radius 4 subtract and you are ...
September 16, 2016

Math
looks like a decimal number with 2 decimal places 4.1x , sum has to be 10 , so 4.15 , 5.1x , ---> 5.14 6.1x, ---> 6.13 7.1x ----> 7.12 8.1x ----> 8.11 could it be 3 decimal places? 4.1xx --- 4.132, or 4.114 or 4.123 or 4.105 etc lot's of cases!
September 16, 2016

Math
number bought at each price ---- x of them so cost = x/10 + x/12 = 11x/60 selling price = 2x/15 difference = 2x/15 - 11x/60 = -x/20 , looks like a loss percent loss = (x/20) / (11x/60) = (1/20)(60/11) = .2727 or appr 27% check: suppose he bough 60 oranges at each price at 10 ...
September 16, 2016

maths
Let their respective prices be 16x and 23x new price of first horse = 1.1(16x) = 17.6x new price of second horse = 23x + 477 17.6x/(23x+477) = 11/20 352x = 253x + 5247 99x = 5247 x = 53 the first horse cost 16(53) or 848 the 2nd horse cost 23(53) or 1219 check: 848 : 1219 = 16...
September 16, 2016

math
first we have to find the payment. let it be p i = .07/12 = .005833.. ----> I stored in my calculator for increased accuracy PV = 220,000 n = 360 p( 1 - 1.0058333...^-360)/.0058333... = 220000 I got p = $1463.67 Value of debt if no payments had been made after 87 periods = ...
September 16, 2016

5th grade math
ONE ONE ----- TWO your answers don't work, since the starting digit of each of the two numbers must equal the unit digit of the answer, namely the O must be the same in all places. Your's isn't case#1 : let E = 1 then: 2N1 2N1 ---- 4W2, how about N = 3, can't ...
September 16, 2016

Math
Total sacks in the harvest ---- x number sold to nearby school = x/3 leaving them with 2x/3 amount used for food = (1/4)(2x/3) = x/6 leaving them with 2x/3 - x/6, or x/2 sacks to be sold to the pupils So .... 8000(x/2) = 216000 x = 2(216000)/(8000) = 54 sacks <---- total ...
September 15, 2016

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