Thursday

November 26, 2015
Total # Posts: 31,843

**Math**

I ignored this question when you first posted it as "Phil" because the poor punctuation and grammar made it hard to understand. e.g. "sales of 58-inch HDTV's are expected to be equal." Equal to what?
*June 22, 2015*

**Algebra**

typo ? I count only 4 marks for the first 5 tests Once you found your error, replace A with your 5th test and solve for x (A+70+80+79+69+x)/6 ≥ 80
*June 22, 2015*

**MATH**

x - 12 - 6 = 2(12+6) take over
*June 22, 2015*

**Math**

mmmh, if it took him 4 hrs to 144.6 miles then in 1 hr he went 144.6/4 or ...... miles if 12 gallons took him 144.6 miles then 1 gallon took him 144.6/12 or .... miles
*June 22, 2015*

**math**

so it must start with a 6 6X,XXX The unit digit can only be 5 so we have 6XXX5 then 6 + 3X+5 = 23 3x = 12 x = 4 your number is 64445
*June 22, 2015*

**Algebra**

Since there is no t term in the equation the ball was "dropped" from a height of 240 ft. So the maximum height was 240 ft
*June 22, 2015*

**math**

umhhh, don't you look back at your previous post ? http://www.jiskha.com/display.cgi?id=1434968282
*June 22, 2015*

**correction - math**

or basic algebra .... let her total amount of money be x x - (1/3)x - (2/5)x = 60 multiply all terms by 15 15x - 5x - 6x = 900 4x = 900 x = 225 Jane had $225 check: snacks = (1/3)(225) = 75 book = (2/5)(225) = 90 , expensive book! amount left = 225-75-90 = 60
*June 22, 2015*

**math**

The fifth digit can only be 4,5, or 6 let's start with the largest case 6X,XX7 , where X is the same 6 + 3x + 7 = 19 3x = 6 X = 2 one case: 62227 if the unit digit is k, it should be clear that 19-(6+k) must be a multiple of 3 and that is true only of x = 2 how about ...
*June 22, 2015*

**math**

Your question is not clearly stated. Do you want the number of elements in a particular subset of a given set? or Do you want the number of subsets possible for a given set? or ... e.g. suppose the have a set of 6 elements such as {A,B,C,D,E,F} The number of subset is 2^6 or ...
*June 22, 2015*

**math**

2^x = 2x no simple formula method to do this type of equation. If you know Calculus , you could use Newton's method. A good way to start is to graph y = 2^x and y = x^2 to see that there are two intersection points. However, they made it easy for you and picked a system ...
*June 22, 2015*

**balayan national highschool**

Possible cases: 3A0AA0 7A4AA2 , where A can be any number from 0-9 since those positions have not been defined If we make the unit digit 4, remember your number has to be even, then the thousand digit is 8 and the hundred thousand digit would be 11 ???? ) Now fill in any ...
*June 22, 2015*

**Calculus(math)**

if v(t) = 2t + 1 then s(t) = t^2 + t + c s(5) = 25+5+c = 30+c s)0) = c effective distance = s(5) - s(0) = 30+c - c = 30 what you found is the difference in the velocities
*June 21, 2015*

**CASS ? Bea ? ALGEBRA**

check for previous post of this http://www.jiskha.com/display.cgi?id=1434803510
*June 20, 2015*

**Calculus**

let the angle be Ø given: dØ/dt = 2° per minute = 2(π/180) radians = π/90 radians (I switched to radians, since trig derivatives are valid for radians) let the third side be x x^2 = 10^2 + 19^2 - 2(10)(19)cosØ x^2 = 461 - 380cosØ 2x dx...
*June 20, 2015*

**ALGEBRA**

If after 20 minutes past "now" the minute hand is just as far ahead of the hour as it is behind, the time then clearly must be 3:30 so 20 minutes ago, it must have been 3:10
*June 20, 2015*

**ALGEBRA**

smaller number --- x larger number ---- x+40 arithmetic mean = (x + x+40)/2 = x+20 geometric mean = √(x(x+40)) x+20 - 2 = √(x^2 + 40x) square both sides x^2 + 36x + 324 = x^2 + 40x 324 = 4x x = 81 one number is 81 and the other is 121 check: AM = (81+121)/2 = 101 ...
*June 20, 2015*

**oops - Ndmc**

Steve is right, I misread the question Nevertheless, that is some dangerous speed the bus is going The math is correct, the bus will catch the car after 20 seconds
*June 20, 2015*

**Second thoughts - Ndmc**

Even though the above solution is mathematically correct, it makes no sense and the question is ridiculous. let's look at what time their speeds are the same 5t = 50 t = 10 after 10 seconds, the bus is going at 50 m/s and the car is going at a constant speed of 50m/s but ...
*June 20, 2015*

**Ndmc**

The question is poorly worded. It says, "At the same time" a car .... overtakes and passes the bus. So the time would be zero. I will assume that the car was a certain distance behind the bus bus: a = 5 v = 5t + c but when t=0, v=0 , so c=0 v = 5t s = distance = (5/2...
*June 20, 2015*

**math**

7 = 1x7 8 = 2x2x2 12 = 2x2x3 Everybody must be represented, so LCD = 1x2x2x2x3x7 = 168
*June 20, 2015*

**geometry**

d miles correspond with 9 inches on the map so 1 mile corresponds to 9/d inches d+1 miles corresponds to (9/d)(d+1) inches on the map doodle with (9/d)(d+1) any way you want.
*June 19, 2015*

**Math**

The period: 2π/k = 5 then k = 2π/5 the amplitude = 35/2 = 17.5 your ferris wheel behaves like h = 17.5sin(2π/5) but you said it is 50 m high and the max height of the function is 17.5 so we need h = 17.5sin(2π/5) + 32.5 looks like I am overthinking this ...
*June 19, 2015*

**algebra**

However, since both sides were squared, all answers must be checked in the original equation √(10-x) + x = 8 if x = 6 LS = √4 + 6 = 8 = RS if x = 9 LS = √1 + 9 = 10 ≠ RS so the only solution is x = 6
*June 19, 2015*

**Math**

how about this approach: Simone's money --- 2x Fiona's money --- 3x after mom's gift: 2x/(3x+5) = 4/7 14x = 12x + 20 2x = 20 x = 10 so Simone had 2x or $20 Fiona had 3x or $30
*June 18, 2015*

**Math (Need help Urgent)**

I am sure you meant: y ≤ -2(x - 2)^2 - 2 which would be everything below and including the parabola, which itself opens downwards and has a vertex of (2,-2) http://www.wolframalpha.com/input/?i=y+%E2%89%A4+-2%28x+-+2%29%5E2+-+2
*June 18, 2015*

**algebra**

amount invested at lower rate --- $x amount invested at higher rate ---$ 3x .02x + .03(3x) = 27.50 times 100 2x + 9y = 2750 11x = 2750 x = 250 so she invested $250 at 2%, and $750 at 3% check: .02(25) + .03(750) = 27.5
*June 18, 2015*

**maths**

let a man's rate be x fields/h let a boy's rate be y fields/h so 2/x + 6/y = 1/3 times 3xy 6y + 18x = xy 6y - xy = -18x y = -18x/(6-x) = 18x/(x-6) , x > 6 also given: x = (2/3)y then x = (2/3)(18x)/(x-6) x(x-6) = 12x x^2 - 18x = x(x-18) = 0 x = 18 (or x = 0, which ...
*June 18, 2015*

**algebra**

looks like an AS, with a = 20 , d = -1 , n = ? (n/2)(2a + (n-1)d ) = sum(n) (n/2)(40 + (n-1)(-1) ) = 200 n( 40 - n + 1) = 400 -n^2 + 41n - 400 = 0 n^2 - 41n + 400 = 0 n = (41 ± √81)/2 = 25 or 16 so term(25) = 20 + 24(-1) = -4 which makes no sense or term(16) = 20...
*June 17, 2015*

**Maths trig**

I am sure you meant f(x) = 3/(x+1) http://www.wolframalpha.com/input/?i=plot+y+%3D+3%2F%28x%2B1%29+%2C+y+%3D-2x-4 look at the 2nd graph, the vertical blue line is an anymptote
*June 17, 2015*

**algebra**

let the number be x 3x - 7 = x + 39 take over, the equation is easy to solve
*June 16, 2015*

**maths**

I have no clue what v =TT is supposed to say, but my formula for volume of a cylinder is V = πr^2 h so for your data, V = π(4^2)(12) = 192π so your can holds a volume of 192π cm^3 which is 192π ml or appr 603.2 ml
*June 16, 2015*

**math**

As Steve pointed out to you in your previous posting of the same question, x = 0 and x = 35 are the values which give you an area of zero, which is not what you want. A = (70-2x)(x) is represented by a parabola which opens downwards, so its vertex shows its maximum and at what...
*June 16, 2015*

**Maths**

using substitution, x^2 - 7x + 23 = 7x - 1 x^2 - 14x + 24 = 0 (x - 12)(x - 2) = 0 x = 12 or x = 2 if x=12, y = 7(12)-1 = 83 if x=2 , y = 7(2)-1 = 13 they intersect at (12,83) and (2,13) confirmation here: look at the first graph http://www.wolframalpha.com/input/?i=plot+Y%3Dx%...
*June 15, 2015*

**calc**

if a(t) = cos(t) − sin(t) v(t) = sin(t) + cos(t) + c given: v(0) = 0 3 = sin0 + cos0 + c 3 = 0 + 1 + c c = 2 v(t) = sin(t) + cos(t) + 2
*June 14, 2015*

**Trigonometry**

But I showed you that it is NOT true, so you can't prove it to be true.
*June 14, 2015*

**Trigonometry**

Hard to prove something which is not true LS= (.11697..)(.41317..)(.9698..) = appr .0469 ≠ 3/2 (I assumed your . meant multiplication, and you were in degrees. It is also false in radians)
*June 14, 2015*

**Math (Finite)**

So you want 2 R's and 1 D prob = C(5,2)xC(6,1)/C(11,3) = 10(6)/165 = 4/11
*June 11, 2015*

**math**

And why do you think it took 4 seconds? (wrong guess by the way)
*June 11, 2015*

**Math Help**

number of choices of any 2 of the 10 = C(10,2) = 45 number of choices of any 2 of the 4 engineers = C(4,2) = 6 Prob(of stated event) = 6/45 = 2/15 or, simply prob(of stated event) = (4/10)(3/9) = 2/15
*June 11, 2015*

**Trig/ algebra 2**

sin(π/2) - cos(π/4) = 1 - √2/2 = (2-√2)/2
*June 10, 2015*

**Functions**

for what function ?? if it is y = cosx then dy/dx = -sinx and -sin(π/4) = -1/√2 so you are correct if y =cosx
*June 10, 2015*

**Probabilities**

let g be good bulb let b be bad bulb so your events are: gbb ---> (4/7)(3/6)(2/5) = 4/35 bgb ---> (3/7)(4/6)(2/5) = 4/35 prob(as stated) = 4/35 + 4/35 = 8/35 or appr .229
*June 10, 2015*

**MATH 117A**

-9x^2 + 7x + 2 = 0 9x^2 - 7x - 2 = 0 x = (7 ± √121)/18 x = 1 or x = -2/9
*June 10, 2015*

**Calculus 1**

you are solving 4.9t^2 - 21.5t - 3 = 0 , after multiplying each term by -1 You must have learned the quadratic equation to be solving these type of questions, go ahead.
*June 10, 2015*

**pre-calculus 11**

is it y = 1/x - c , like you typed it, or y = 1/(x-c) comparing it to y = 1/x for the first interpretation the graph of y = 1/x would simply be translated vertically by c for the 2nd interpretation the graph of y = 1/x would be translated horizontally by -c , e.g if y = 1/(x+2...
*June 10, 2015*

**pre-calculus 11**

from the definition of absolute value, we know the right side must be ≥0 so x+1 ≥ 0 x ≥ -1 algebraically: (1/2)x + 1 = x+1 OR (-1/2)x - 1 = x+1 x + 2 = 2x + 2 OR -x - 2 = 2x + 2 x = 0 OR -3x = 4 x = 0 or x = -4/3 which is what you had remember at the top we ...
*June 10, 2015*

**pre-calculus 11**

let's look at the graph. http://www.wolframalpha.com/input/?i=plot+y%3D-%7Cx%5E2+-9%7C+%2C+x+from+-10+to+10 notice that the entire graph must lie below the x-axis, since we have y = -(some positive stuff) so for x<-3 OR x>+3, we have y = -x^2 + 9 for -3 ≤ x &#...
*June 10, 2015*

**Precalc**

we know sinØ = y/r and cosØ = x/r and tanØ = y/x then for the given: sinØ = x = y/r rx = y ---> r = y/x 3cosØ = y = 3x/r ry = 3x (y/x)y = 3x y^2 = 3x^2 y = ±√3 x
*June 10, 2015*

**math help trigonometry**

yup, that's what you typed the first time. And I pointed out to you that that is not an identity.
*June 10, 2015*

**math help trigonometry**

tan x cos x/sin x=1/sin x cos x or tan x cos x/sin x=1/(sin x cos x) ? For either case, LS = tanx(cosx/sinx) = tanx cotx = 1 For any given x, RS ≠ 1 Your equation is NOT an identity, so it cannot be proven to be true.
*June 10, 2015*

**Algebra**

2nd: 10x^2 + 70x + 100 = 10(x^2 + 7x + 10) = 10(x+5)(x+2) 3rd: 2x^2 + 9x + 4 = 0 (2x + 1)(x + 4) = 0 carry on 4th: real easy ... (x-5)^2 - 81 = 0 (x-5)^2 = 81 take √ of both sides x-5= ±9 x = 5 ± 9 = 14 or -4
*June 10, 2015*

**Geometry**

If I read this correctly, the radius of his model is 6 inches Volume of sphere = (4/3)π r^3 = (4/3)π(216) = 288π cubic inches or appr 904.8 cubic inches SA = 4πr^2 = 4π(36) = 144π inches^2 or appr 452.4 inches^2 to double the radius results in ...
*June 9, 2015*

**Geometry**

As the question suggests, the line joining your two points is a diameter. So the centre is the midpoint, which is ((-5+11)/2 , (-11+19)/2 ) = (3, 4) radius = √(3+5)^2 + (4+11)^2 = √(64+225) = √289 = 17 equation of circle: (x-3)^2 + (y-4)^2 = 289 if x = 24 21^...
*June 9, 2015*

**Geometry**

Where is E ? Where is P ? Are your given points A,B,and C on the circle?
*June 9, 2015*

**Geometry**

Have you learned about b^2 - 4ac, called the discriminant, of the quadratic equation? If the discriminant is zero, there is only one solution, so evaluate b^2 - 4ac. If the discriminant is positive, there are 2 real and different solutions, If the discriminant is negative, ...
*June 8, 2015*

**Math**

5/36 is correct
*June 8, 2015*

**Geometry**

from the linear equation: x = 7y - 75 intersect the two relations, x^2 + y^2 = 225 (7y-75)^2 + y^2 - 225 = 0 49y^2 - 1050y + 5625 + y^2 - 225 = 0 50y^2 - 1050y + 5400 = 0 divide by 50 y^2 - 21y + 108 = 0 (y - 12)(y - 9) = 0 y = 12 or y = 9 if y = 12, x = 9 if y = 9 , x = -12 ...
*June 8, 2015*

**calculus1**

Did you make a sketch? Here is Wolfram's take on the situation. http://www.wolframalpha.com/input/?i=plot+y%3D3x%2Cy%3Dx%2Cy%3D4-x You need the intersection of the lines I assume you want the area of the enclosed region. the intersection points are (0,0), (1,3), and (2,2) ...
*June 8, 2015*

**math**

perimeter = 1 length + 2 width + (1/2)circumference of circle = 16 + 2(7) + (1/2)(2π)(8) = 30 + 8π = appr 55.13 using a better value than 3.14
*June 8, 2015*

**Algebra**

Joanie's equation is (x+16)(x-2) = 0 x^2 + 14x - 32 = 0 , in hers the -32 is wrong, the 14x is correct Kelvin's equation is (x+36)(x-2) = 0 x^2 + 34x - 64 = 0 for his, the 34x is wrong , but the -64 is right the teacher's equation is x^2 + 14x - 64 = 0
*June 3, 2015*

**math**

take two identical rulers and lay them across each other at 30° to get a mental image of the problem. Is the overlapping area not a rhombus with acute angles of 30° and obtuse angles of 150° ? So make that sketch, all 4 sides are equal, label them x draw a vertical...
*June 3, 2015*

**math**

I don't know what your diagram looks like, but try this I will assume that this is a question dealing with vectors. let O be the centre of you NS, EW grid draw a line OB with a heading of N65°W , and mark it x km/h this will be your resultant vector draw in your wind ...
*June 3, 2015*

**Math**

arggh, go with Damon on the first question, I read it as 1/3 of the time, not 1/3 hour less
*June 3, 2015*

**Math**

rate at first part --- x mph rate for return --- x + 5 mph time on first part = 120/x time on 2nd part = 120/(x+5) (these should be entries in your chart) now it says: time on return = (1/3) time of first part 120/(x+5) = (1/3)(120/x) divide by 120 1/(x+5) = 1/(3x) 3x = x+5 2x...
*June 3, 2015*

**Algebra**

One 12 oz can = 12(29.6) ml or 426.4 ml so a six pack = 6(426.4) ml or 5116.8 ml cost of 2 L bottle = $2.19/2000 ml = .001095 $/ml cost of six pack = 2.99/5116.8 = .00058 $/ml draw your conclusion
*June 3, 2015*

**Algebra**

1 litre costs 1.31 1 gallon = 3.7854 L 12 gallons = 12(3.7854) L 12 gallons cost CND $1.31(12)(3.7854) = CN $59.51 1 CND = US 1.02 C 59.51= US (1.02)(59.51) = $60.70 cost per gallon in US$ = 60.70/12 = $5.06 actual cost TODAY: 12 gallons cost 12(3.7854)(1.06) = $48.15 CND $1...
*June 3, 2015*

**algebra**

I bet you meant: x^2/(x+4) ÷ ( (x-2)/(x^2+x-12) ) = x^2/(x+4) * (x+4)(x-3)/(x-2) = x^2(x-3)/(x-2) , x ≠ -4,2
*June 3, 2015*

**Geometry.**

Steve is right, pardon the senior moment, and my diagram even has D corresponding with A
*June 3, 2015*

**Geometry.**

angle A = 180-121-35 = 24° since angle FDE corresponds with angle CAB angle D = 35°
*June 3, 2015*

**Calculus**

At a stop, the velocity is zero, so t^3 - 3t^2 + 3t = 0 t(t^2 - 3t + 3 ) =0 t = 0 or t^2 -3t + 3 = 0 t^2 - 3t + 3 = 0 has no real solution to slow down a(t) would have to be negative a(t) = 3t^2 - 6t + 3 let's see where it is zero t^2 - 2t + 1 = 0 , after dividing both ...
*June 3, 2015*

**probability**

9 cars, 3 of which are red so prob(red,red) = (3/9)(2/8) = 1/12 you do the decimal stuff
*June 2, 2015*

**Math**

cos^4 Ø - sin^4 Ø + sin^2 Ø = (cos^2 Ø + sin^2 Ø)(cos^2 Ø - sin^2 Ø) + sin^2 Ø = (1)(cos^2 Ø - sin^2 Ø) + sin^2 Ø = cos^2 Ø
*June 2, 2015*

**Math**

Took me a while, but I was sure that Steve had answered this for you http://www.jiskha.com/display.cgi?id=1432887186 and again here http://www.jiskha.com/display.cgi?id=1432801604
*June 2, 2015*

**Algebra**

I have a feeling you meant: (x+2)/8 + 1 = 4x/2 multiply each term by 8 x+2 + 8 = 16x 10 = 15x x = 10/15 = 2/3
*June 2, 2015*

**Math**

the first chair can be filled in 8 ways, for each of those the 2nd chair can be filled in 7 ways, (one is seated) and for each of those, the 3rd chair can be filled in 6 ways, so number of ways = 8*7*6 = 336 ways
*June 2, 2015*

**Algebra**

9y/7 = 12y - 24 times 7 9y = 108y - 168 99y = 168 y = 168/99 y = 56/33
*June 2, 2015*

**Math**

nope, what you wrote is the opposite of what you had That is like saying can 5 be written as -5 ?
*June 2, 2015*

**Math**

one problem, you should have brackets around n-1 so a(n) = 5(-2)^(n-1) otherwise, good job
*June 2, 2015*

**Algebra**

divide both sides by -9 (4-k)/12 = -(k+1)/8 cross-multiply 8(4-k) = -12(k+1) 32 - 8k = -12k - 12 4k = -44 k = -11
*June 2, 2015*

**Alegebra**

multiply each side by 12 7(w+2) = 4(w-7) 7w + 14 = 4w - 28 3w = -42 w =-14
*June 2, 2015*

**Algebra 1**

You first started asking this question under the name of Gabs, now you are Amy The above question is clearly based on some previous problem which we cannot see. e.g. how can we possible know how many men and how many women are in the cast?
*June 2, 2015*

**math**

I agree
*June 2, 2015*

**Math**

let's start with dimes ---- x then quarters ---- x+8 nickels ------- 5(x+8) now to the VALUE of these 10x + 25(x+8) + 5(5)(x+8) = 700 10x + 25x + 200 + 25x + 200 = 700 60x = 300 x = 5 so 5 dimes 13 quarters 65 nickels check: 5(10) + 13(25) + 65(5) = 700 my answer is correct
*June 2, 2015*

**math**

You started off ok, but then your logic exploded. You only have to consider the unit digit listing only the unit digit: 2^1 -- 2 2^2 -- 4 2^3 -- 8 2^4 -- 6 2^5 -- 2 2^6 -- 4 2^7 -- 8 2^8 -- 6 .... notice they cycle 2,4,8,6 If the exponent is evenly divisible by 4, the last ...
*June 2, 2015*

**mathh**

number of 5's --- x number of 7's ---- y 5x + 7y = 130 5x = 130-7y x = (130-7y)/5 x must be a whole number, so 130-7y must be divisible by 5, only if 7y is a multiple of 5 to get the least number of stamps we should use as many of the 7's (the y) as we can if y = ...
*June 2, 2015*

**Math**

in effect, each day the turtle gains 2 ft after 1st day/night -- 9 after 2nd day/night -- 7 after 3rd day/night ---5 after 4th day ---- since he crawls 5 ft during the day, he is at the top at the end of the 4th day.
*June 2, 2015*

**Algebra 1**

ok, I misread your question total number of castings = 35 number of casting with the one brother and sister = 1 number of castings with the one brother and two sisters = 1 x 2 = 2 prob (bother and sister in casting) = 3/35
*June 2, 2015*

**Algebra 1**

missing information. In what way are the sibling choices affecting the casting? e.g. can the 2 siblings not be cast together?
*June 2, 2015*

**Algebra 1**

no, any of the 7 men could have the leading role, for each of those, there would be 5 choices for the female role, so number of ways = 7x5 = 35
*June 2, 2015*

**Algebra 2**

Nothing wrong in your steps, except at the end when you have x = 3 or x = -2, we can't allow x = 3, since we then would have divided the original by zero, which we can't do so the only answer is x = -2 Had you factored like in the previous .... (x+5)(x-3)/(x-3) = 3 x+5...
*June 2, 2015*

**Algebra 2**

(x^2+bx-18)/(-2x+4) = 4 = 4/1 same as before, cross-multiply x^2 + bx - 18 = -8x + 16 now let's sub in the x = -17 (-17)^2 - 17b - 18 = 136 + 16 -17b = 152 + 18 - 289 -17b = -119 b = 7
*June 2, 2015*

**Algebra 2**

So I read that as: (x^2-7x+12)/(x^2+x-12) = 3 (x-3)(x-4)/((x+4)(x-3)) = 3 (x-4)/(x+4) = 3/1 cross-multiply 3x+12 = x-4 2x = -16 x = -8
*June 2, 2015*

**Algebra**

give it a try, this one is really easy
*June 1, 2015*

**alegbra2**

50 = 40(1.08)^n 50/40 = 1.08^n n log 1.08 = log(5/4) n = log(5/4) / log 1.08 = 2.899 or appr 2.9 years check: 40(1.08)^2.9 = 50.002 Your expression is incorrect
*June 1, 2015*

**Algebra**

times 6 -66(5-b) = 3b -330 + 66b = 3b 63b = 330 b = 330/63 = 110/21
*June 1, 2015*

**Math**

The LCM of 7,11, and 30 = 7*11*30 = 2310 So 2311 would not divide by any of those, in each case there would be a remainder of 1
*June 1, 2015*

**Math**

multiply each term by 11 10v + 110 = 88(v-7) 10v + 110 = 88v - 616 -78v = -726 v= 121/13
*June 1, 2015*

**Maths**

I assume you want to find the surface area a) two circle + a rectangle = 2π(5^2) + 2π(5)(13) = 50π + 130π = 180π = appr 565.49 cm^2 (Nobody would use π as 3.1 in 2015) b) if it is open at one end, the use only one circle and repeat my steps
*June 1, 2015*

**math**

amount of 45% stuff --- x ml amount of 15% stuff ---- 780-x mls .45x + .15(780-x) = .35(780) times 100 to get rid of decimals 45x + 15(780-x) = 35(780) take over from here
*June 1, 2015*