# Posts by Steve

Total # Posts: 54,314

Math
assuming 30-day months, that would be 90 * 30 * 24 If you want to adjust some you could note that 90 months is 7.5 years, so 7.5 * 365 * 24 of course, you could also toss in 1 or 2 leap years, if you insist.

math
3n-44 = -19 or 44-3n = -19

Math
oh come on. I showed you two examples. Surely you can do arithmetic.

Math
If f(n) = 5^n then f(1) = 5^1 = 5 just replace all the n's with whatever you want. If that's numbers, then you can evaluate the result. f(n) = -n f(-3) = -(-3) = 3 and so on.

Geometry
oops. Divide that by 4, since the sizes were diameters, not radii. 5000pi mm^2

Geometry
the shaded area is the difference between the two areas: pi(150^2-50^2) = 20000pi mm^2

Math
150, I guess.

Science
no way to tell, if the rock sinks. All we know is that the rock occupies 6 ml of volume.

math
Uh, well, I started out with no contents, then filled the 8-cup container. Then from the 8-cuo, I filled the 5-cup, leaving 3 and 5 cups in the two. Then empty the 5-cup pour the 3 cups from the 8-cup into the 5-cup Refill the 8-cup pour from it till the 5-cup is full, leaving...

math
let the contents of the cups be 8 0 3 5 3 0 0 3 8 3 6 5

math
do the parentheses first. Then you have 2x2x2 + 10/2 then the multiply/divide 8+5 then the add 13

math
well, 8 = 4x2, so ...

Math
since h(0)=0 and h(30)=0, the vertex must be at t=15 h(t) = 45-a(t-15)^2 45-a*15^2 = 0 225a = -45 a = -1/5 h(t) = -1/5 (t-15)^2 + 45

Math
#6: Associative Property of Addition there's no multiplication going on.

Math
a) since the vertex is at (16,11), the x-intercepts are at x=0 and x=32: y = ax(x-32) where a<0 11 = a*16^2 a = 11/256 y = 11/256 (32-x^2) b) now just solve for x when y=1.9 c) the ball can be going up or down when the player heads it.

science
there are 0.050 * 0.0875 = 0.004375 moles of NaOH. HClO4 + NaOH -> NaClO4 + H2O So, you need that many moles of HClO4 0.004375 moles / (0.115 moles/L) = 0.038L or, 38mL of .115M HClO4 solution

Physical Science
#1 correct #2C dew condenses on the grass at night it evaporates (vaporizes) in the sun during the say. CO2 sublimes: goes from solid to vapor without a liquid phase. Hence, dry ice.

maths
5400/13.50 = 400 ?400 = 20 4*20*28.50 = 2280.00

chemistry
it is homogeneous because the two liquids (alcohol and water) are smoothly mixed. google will provide many examples of what makes mixtures homogeneous.

math
3 5/6 - 3/4 = 3 10/12 - 9/12 = 3 1/12

math
Let x = Juan's share x+4 = John's share 2(x+4) = Jenna's share so, add 'em up to 60, solve for x, and then you can figure the shares.

math
40 + 1.2 + .25 = 41.45 30 + 1.4 + .045 = 31.445 41.450 - 31.445 = 10.005 or 1 ten 5 thousandths

calculus
average velocity is totaldistance/totaltime the minimum x is at t=3.50, so x(3.00) = 6.80 x(3.50) = 4.50 ?x/?t = -1.7/0.5 = -3.4 ft/s If you do want to devise a function, then you see that x(2.90) = x(3.60) = x(4.00) = 7.65 So, since x is falling at t=2.90 and again at t=4.00...

Math
let's say you have exactly twice as many bars as he. So you have 1340 and he has 670 So, as long as you have at least 1340, but fewer than 2009 bars, he has some, and you have at least twice as many.

Math
16 + 10*2 / 5 = 20

Math
Oops. That's 490, as Ms. Sue said, but the answers stay the same.

Math
a work day has 15+60*7+55 = 485 minutes (1) 485/35 = 13.8 (ii) 485/31 = 15.6

Math
#1 yes #3 yes #2 hmmm either 5(x-10)+x = 6x-50 or 5(x+10)+x = 6x+50

Geometry Probability
Do swimmers count among those who like sports? If not, then There are 17 swimmers, so P(boy if swimming) = 8/17 = .47 There are 27 sports, so P(girl if sports) = 7/27 = .26 Adjust the numbers if swimmers are counted among "sports" and so on. How did you get your ...

Algebra help pls
#1A "sum" means add. "product" multiply. #2C I have no idea how you came up with your answer. If you meant x/3 = 12 then multiply both sides by 3, since 3/3 = 1. Then you have x = 36 You did the multiplication, and then added another 3. Why? 39 is the ...

Algebra help pls
substitute the numbers for the variables. Does 5 = 3*2-1? Yes

physics
sorry - I misread your other post. The answer here is much simpler. 58 km/hr = 16.11 m/s distance = speed * time = 16.11 m/s * 0.742s = 11.95m

physics

physics
58 km/hr = 16.11 m/s Now use your usual formula for distance to get 5.98m

maths
sin2x+3cosx = 2 2sinxcosx+3cosx = 2 cosx(2sinx+3) = 2 2sinx+3 = secx cos3x = cos2xcosx-sin2xsinx = cos2xcosx-(2-3cosx)(2-3cosx)/(2cosx) = (2cos^2x-1)cosx-(2-3cosx)^2/(2cosx) I don't see where this is going. I fear that I am missing something here if you expect some simple ...

Differentiation
n is a constant. Usually variables are letters in the last part of the alphabet. So, if you mean x^(n+1) / (n+1) then using the power rule, the derivative is (n+1)x^(n+1-1) / (n+1) = x^n If you meant what you wrote, then the derivative is (nx^(n-1)+0)/(n+1) = n/(n+1) x^(n-1) ...

Math
"what number" is x, so .005x = 15 ...

Precalculus
For #3, (f?g)(x) = f(g) = g^2/(g^2-1) = (x+4)/(x+3) Since f(g) is not defined for g^2=1 x = -3 must be excluded g(x) is undefined when x < -4 x = 1,-1 are in the domain of f?g even though they are not in the domain of f.

C, because If you throw it up with a speed of 11 m/s, it will have that same speed downward when it returns to the top of the building.

Physics
It indicates that you have been using a measuring device with a .001 precision.

chemistry
191x + 193(1-x) = 192.23 x = .385 so, 38.5% Ir191 61.5% Ir193 or, since 192.23 is about 5/8 of the way from 191 to 193, 5/8 will be Ir193, or 62.5%. Fairly close ...

maths
LS: (1+tan^2)/(1+cot^2) * tan^2/tan^2 = tan^2(1+tan^2)/(tan^2+1) = tan^2 RS: (1-tan)^2/(1-cot)^2 = [(1-tan)/(1-cot)]^2 = [(1-tan)/(1-cot) * tan/tan]^2 = [tan(1-tan) / (tan-1)]^2 = [-tan]^2 = tan^2 LS = RS

Math
when dividing, subtract exponents. 7^8/7^2 = 7^(8-2) = 7^6 Think about it. What you have is 7*7*7*7*7*7*7*7 -----------------------        7*7 two of the factors cancel out, leaving 7^6 in the top.

Math
s = t+3 s = 2h t = h+2 so, let's solve for Hannah. t = h+2 t+3 = 2h, so t = 2h-3 That gives us h+2 = 2h-3 h = 5 So, Hannah is 5, Tim is 7, Steve is 10 (which is twice as old as Hannah)

Maths
another way to do it is to use the cot function. If the pole's height is h, then h cot67° + h cot 58° = 21 So, h = 21/(cot67°+cot58°) Then using h, the lengths of the wires are h csc 67° and h csc 58°

Math
Take a look at the Fundamental Theorem of Arithmetic.

yeah, what about it? "bisect" means it divides into two equal parts.

Geometry
JK+KL=JL 2x+1 + 8x = 81 x = 8

math
Add up the amounts of anti-freeze in the parts and the mixture. They must be the same. If x gallons of 100% anti-freeze are added, then .10*10 + 1.00x = .60(10+x)

Math
L1 has slope -5/8 L2 must have slope 8/5 So, the point-slope form of L2 is y-10 = 8/5 (x-10) y = 8/5 x - 6 m+b = 8/5 - 6 = -22/5

geometry
x: (7-1)/2 = 3 y: (3-3)/2 = 0 so, the midpoint is (3,0)

thank you

Robert borrowed \$750 from his parents to make some repairs on his car. He promised to repay the loan by giving his parents at least \$67 from his paycheck each week. Assuming Robert sticks to his promise, which of the following is not a possible scenario for the amount of debt ...

Reiny, there is no typo because what you put is what I would have said but based on the choices offered it's not that easy.

I believe #4 is correct. The original balance in Rudolph's account is -650. Using 76x-650, you are correct that the balance in the account after 5 weeks is -270. But, suppose he paid \$80 each week. Then the balance would be 5*80-650 = -250. But -250 >= -270. Actually, I...

Rudolph borrowed \$650 from his parents to make some repairs on his car. He promised to repay the loan by giving his parents at least \$76 from his paycheck each week. If x represents the number of weeks, which linear inequality represents the amount of debt Rudolph has ...

furth math
h + 2h+5 - 15 = 180 3h = 190 Hmmm. h must be an integer. I suspect a typo 63+131-15 = 179 64+133-15 = 182

College Algebra
There is no way to mix \$9/lb and \$6/lb nuts to make a mixture that costs \$127/lb. I assume you posted the other similar nuts question, since it has the same mistake. See the solution to that one for the method for this one.

Math
see your previous ice rink question for the method to solve.

College Algebra
See your previous similar question for the method of solution.

Math
the diagonal of the square is the same as the diameter of the circle. So, the diagonal is 0.35m L = 0.35/?2 m

Math @Reiny
Maybe oops. This question has been posted more than once, with differing numbers, just like the almonds/macadamia question and the walking/cycling questions.

Math
120-36 = 84 84 = 2*2*3*7 See what you can do with that.

College Algebra
g+y = 90 10g+6y = 900 ...

Math
1:30 to 2:15 = 3/4 hour 2:15 to 3:00 = 3/4 hour If his walking speed is w, then we have 3/4 * 3/2 w + 3/4 * w = 9.375 = 75/8 Now just solve for w...

Math
we want the *sum* to exceed 5000 ...

Math
Just use your formula for an arithmetic sequence n/2 (2*7+(n-1)*5 > 5000 n > 44 So, the 44th term is 7+43*5 = 222 check: 43/2 (14+42*5) = 4816 4816+222 = 5038

Math
what do segments have to do with boxes?

Math
Take a look at the differences. 2,3,9,23,48,87 1,6,14,25,39 5,8,11,14 3,3,3 The3rd difference is constant, so you need to find a cubic polynomial. I came up with 1/2 (n^3-n^2-2n+6) or 3 + (n-2)(n)(n+1)/2

Algebra
Since you have the vertex, use that for the equation. y = a(x-7)^2 - 2 Now just plug in your other point to find a.

Math
Hard to say, but I think you want P such that P*.08*15/2 = 1770

math
plug in your two points: 2/a + 8/b = 1 1/a + 5/b = 1 multiply the 2nd by 2 and you have 2/a + 8/b = 1 2/a + 10/b = 2 now subtract, and you have 2/b = 1 b = 2 use that to find that a=-2/3 x/(-2/3) + y/2 = 1 check the intercepts and you see that they are (-2/3,0) and (0,2) Now ...

College Algebra
distance = speed * time, so we have k = c+2 6k = 9(k-2) 3k = 18 k = 6 check: 6*6 = 4*9

College Algebra
add up the value of each part of the mix. Note that the \$95.75 is the total cost, not the cost per pound. 4.75x + 8(14-x) = 95.75

College Algebra
do this one the same way as the previous coin problem. Add up the values and use the information about how many coins there are.

College Algebra
24a+14=6(8a+3)-26a+4 24a+14 = 48a+18-26a+4 24a-48a+26a = 18+4-14 2a = 8 a = 4

College Algebra
just add up the coins and their values. 5n+10d = 80 n = d+5 Now just solve for n and d 10 nickels, 3 dimes

unt
25^x = 77 x log25 = log77 x = log77/log25 or, if you originally took logs base 25, x = log25</sub?77

Algebra
well, ?2 ? 1.414 so just multiply that by 4

Math
if there are 2 new frogs, then that means the population has tripled. After t years, there will be P(t) = 0.5 * 3^t kF

Math
2r-15

Marh
the volume of the sphere is 972? cm^3 since the area of the tank's cross-section is 144? cm^2, the height of the water column occupied by the sphere is 972? / 144? = 6.75 cm

Math
#1 "sum" means addition, not subtraction, so D: 7/(3+z) #2 correct #3 correct, if "7" was supposed to be "y" #4 correct

Spanish
yes

\math/
just multiply top and bottom 2/3 * 1/2 = (2*1)/(3*2) = 1/3 or, since half of 2 is 1, 1/2 of 2 boxes is 1 box 1/2 of \$2 is \$1 ... half of 2/3 is 1/3

Maths Mensuration
oh, man -- I missed it!

Maths Mensuration
well, it's 1/6 + 3/6 + 2/6 so what do you get?

Maths Mensuration
trace around a book

science
SnCl2 + 2HgCl2 --> Hg2Cl2 + SnCl4

Physics
For comparison, change all to m/s: 36 km/hr = 36000m/3600s = 10 m/s .8km/min = 800m/60s = 13.33 m/s A takes 100 seconds to reach Q. By that time, B has reached R C has passed S and is 33.33 m toward P So, BC = ?(1000^2 + 33.33^2) meters Since A and B are both moving at 10 m/s...

math
Draw two intersecting lines, using the straightedge. The lines form an angle. Label the vertex of the angle as point O. Set the compass to a convenient radius and using point O as the center, draw a circle. The circle will cut the sides of the angle. Label the two points of ...

Statistics
100

Math
I think you want to say that the width is w. So, the length is 3w-9. If so, then you have 2(w + 3w-9) = 342 Now just solve for w.

Math
-6 + 3*1 = -3

Math
Because f is continuous in the specified interval, the Intermediate Value Theorem applies. It can't get from 5 to -5 without assuming every value in between. In particular, zero.

Math
the only pairs of such integers are 1,34 2,17 -2,-17 -1,-34 so, what do you think?