Thursday

November 20, 2014

November 20, 2014

Total # Posts: 1,494

**intermediate math**

Recall that distance is equal to rate (or speed) mutiplied by time: d = v*t Let r = speed of Payton Let r + 4.5 = speed of Angie If they are jogging opposite to each other, then the distance between them is equal to the sum of their rates multiplied by the time: d = r*t + (r+4...
*September 29, 2014*

**chemistry**

Recall Boyle's Law: P1 * V1 = P2 * V2 where P1 = initial pressure P2 = final pressure V1 = inital volume V2 = final volume This is applicable if Temperature is held constant. Substitute the given values and solve for P2. Hope this helps~ :)
*September 28, 2014*

**Chemistry- colligative properties**

Van't Hoff factor can be associated to the property of the substance (if it's strong electrolyte, weak electrolyte, etc.), and can be approximated by counting the number of ions dissociated in water. a. i ~ 1 (weak acid, therefore weak electrolyte) b. i = 2 (strong ...
*September 28, 2014*

**Physics**

Formulas we need (uniformly accelerated motion): h = vo*t - (1/2)gt^2 vf^2 - vo^2 = 2gd Let H,t be the height of tower. The first stone thrown upward reaches its maximum height, h,max = vo^2 / 2g h,max = 15^2 / 19.6 h,max = 11.4796 meters (above the tower) and the time needed ...
*September 28, 2014*

**mathematics**

A bag contains 10 red, 15 white, 25 green balls. What should be the minimum number of balls drawn without replacement so that you get 5 red, 3 white, 10 green balls.
*September 9, 2014*

**college algebra**

A large rectangular movie screen in an IMAX theater has an area of 7200 square feet. Find the dimensions of the screen if it is 10 feet longer than the width.
*September 6, 2014*

**Calculus**

f(x)=sqrt(x^3+2) We can also rewrite this as, f(x) = (x^3 + 2)^(1/2) Then we can use chain rule, f'(x) = (1/2)*(3x^2)*(x^3 + 2)^(-1/2) Finally, the second derivative is f''(x) = (3/2)(2x)(x^3 + 2)^(-1/2) + (3/2)(x^2)(3x^2)(-1/2)(x^3 + 2)^(-3/2) And simplify. Hope ...
*May 16, 2014*

**geometry**

Recall the Pythagorean theorem: c^2 = a^2 + b^2 where c is the hypotenuse (which is also the longest side of a right triangle) and a & b are the legs. Substitute each side lengths to the equation. Of course the longest side is c, and the remaining sides are a and b. If the set...
*May 16, 2014*

**phys**

A boat is traveling upstream at 14 mph with respect to a river that is flowing at 6 mph (with respect to the ground). A man runs directly across the boat, from one side to the other, at 6 mph (with respect to the boat). The speed of the man with respect to the ground is:
*February 19, 2014*

**Math - Check my answer?**

Yes that's correct.
*January 8, 2014*

**Math check**

1. Actually it's B. Expanding, 2(x - 3) = 2x 2x - 6 = 2x -6 = 0 Note that if you get an answer like this (constant = zero), there is no solution. 2. It's D. (btw I don't know why you put question mark beside 3) Expanding, 3(y - 3) = 2y - 9 + y 3y - 9 = 3y - 9 or 0...
*January 8, 2014*

**algebra**

Let A = number of sweets of Alvin Let C = number of sweets of Calvin Let M = number of sweets of Melvin According to the statements, A < C A + C = 31 M = A + 24 Note that to maximize M, A should also be maximized. Maximum value of A is 31 (that is, if C = 0), but according ...
*December 30, 2013*

**geometry**

Recall that surface area of cone is SA = pi*r^2 + pi*r*s where r = radius s = slant height Substituting, SA = 3.14 * 15^2 + 3.14 * 15 * 11 SA = 706.5 + 518.1 SA = 1224.6 sq units Hope this helps :3
*December 29, 2013*

**MATHS**

Area of disc (circle): A = pi*r^2 A = 3.14 * 7^2 A = 153.86 cm^2 Area of cardboard (rectangle): A = L * W A = 70 * 50 A = 3500 cm^2 Divide area of rectangle by area of circle: 3500 / 153.86 = 22.75 Take only the whole number: 22 discs Hope this helps :3
*December 29, 2013*

**Genius Math**

Hmm, the triangle seems impossible, because if you draw it, given the condition that AC = BC (thus it's an isosceles triangle), then angle ACB = 96, therefore BAC = 96 degrees also (since the sides opposite to the angles are equal). So if there are two angles which are 96...
*December 24, 2013*

**Chemistry**

When naming alkanes, alkenes, alkynes, yes, it's the longest chain that is first counted. And then identify the groups attached to to. (For instance methyl, ethyl, etc). Then number the carbon in the longest chain, starting from the nearest attached group (if it's ...
*December 21, 2013*

**Mechanics**

Recall that Pressure is just Force over a unit Area, or P = F/A We are given the force (which is 220 N), therefore, we only need to find area. A = L*W A = 4*3 = 12 m Therefore, P = 220 / 12 P = 18.33 N/m^2 P = 18.33 Pa Hope this helps :3
*December 21, 2013*

**math**

Find the value of df^-1/dx at x=f(a). f(x)=5x+8, a=-1 i got 5?
*December 19, 2013*

**science**

That's correct. :)
*December 18, 2013*

**Algebra 1**

Let x = weight of chicken in pounds Let y = total cost of x pounds of chicken Therefore, y = 2.99x To see the graph of this, go to wolframalpha . com and type in the equation. Hope this helps :3wol
*December 18, 2013*

**math**

f(x) = 7x - 2
*December 18, 2013*

**algebra**

Substitute T = 141 to the equation: 141 = –0.005x^2 + 0.45x + 125 Simplify: –0.005x^2 + 0.45x + 125 - 141 = 0 –0.005x^2 + 0.45x - 16 = 0 Recall that discriminant is just D = b^2 - 4ac if D < 0 : imaginary root D = 0 : real, equal root D > 0 : two real, ...
*December 18, 2013*

**Pre-Calculus**

*I mean you get all the factors of x = +/- p/q. In the problem, x = +/- 20, and its factors are written there above. The factors are the ones you have to check by substituting them to the expression. :)
*December 16, 2013*

**Pre-Calculus**

You use rational root theorem. Let p = constant term Let q = numerical coefficient of highest degree of x x = +/- p/q In here, p = -20 and q = 1. Thus, x = (+/-) 1 , 2 , 4 , 5 , 10, 20 You have to substitute each factor (for instance x = -1) to the expression, and if you get a...
*December 16, 2013*

**Math Quick Question**

You spoke to that person for 45 minutes only.
*December 8, 2013*

**Chemistry(DrBob222)**

Yes, that's right. :)
*December 8, 2013*

**math**

1/13 = 0.0769230769230... The repeating numbers are 076923 (six numbers), thus, 43 / 6 = 7 remainder 1. Therefore counting from zero, the 43rd digit after the decimal point is 0. hope this helps. :3
*December 7, 2013*

**Math**

1. No 2. Parallel
*December 7, 2013*

**Math**

x + 7 ≥ 3x x - 3x ≥ -7 -2x ≥ -7 x ≤ 7/2 x ≤ 3.5 3x + 4 ≤ 5x 3x - 5x ≤ -4 -2x ≤ -4 x ≥ 2 Therefore, the common solution is from 2 to 3.5, or 2 ≤ x ≤ 3.5 Hope this helps :3
*December 7, 2013*

**algebra**

d = 0.05r^2 + r Substitute r = 45: d = 0.05(45)^2 + 45 d = 101.25 + 45 d = 146.25 ft To the nearest foot, d = 146 ft Hope this helps :3
*December 7, 2013*

**math**

h(n) = 100 / 9 n Substitute n = 27: h(27) = (100 / 9) * 27 h(27) = 100 * 3 h(27) = 300 dollars hope this helps :3
*December 7, 2013*

**math**

12 - q ≥ -13 Just solve it like a true equation: 12 + 13 ≥ q 25 ≥ q or q ≤ 25 Hope this helps :3
*December 7, 2013*

**Chemistry**

Formula to be used: Molality = moles of solute / kg solvent Steps: #1. To do this, get the molar mass of Tin, using a periodic table. Fomula for Tin in Sn (look it up in the periodic table, and you'll see its mass). #2. After you get the mass of Tin, divide it by 5 g, and ...
*December 4, 2013*

**Chemistry**

*repost* Formula for osmotic pressure: Π = MRT * i where m = molarity (mol solute / L solution) R = universal gas constant = 0.0821 L-atm/mol-K T = temperature (K) i = van't Hoff factor (approximately equal to ionizable ions) Note that sucrose is soluble in water, but...
*December 4, 2013*

**Chemistry**

Formula for osmotic pressure: Π = MRT * i where m = molarity (mol solute / L solution) R = universal gas constant = 0.0821 L-atm/mol-K T = temperature (K) i = van't Hoff factor (approximately equal to ionizable ions) Note that sucrose is soluble in water, but does not...
*December 4, 2013*

**Algebra 1**

Yes, your answer is correct. :) (I thought at first the radius is 2 and 1/2, not 21/2, but I guess that's too small) :3
*December 4, 2013*

**Geometry**

Use Heron's formula. Let a, b and c be the sides of a triangle. Let s = a + b + c Therefore the area of triangle can be calculated using this formula: A = sqrt[ (s)(s-a)(s-b)(s-c) ] It should be a little easy using this formula, so I guess you can do it on your own. :) ...
*December 4, 2013*

**Calculus**

limit (sin(4x+12))/(5x+15) as x -> -3 If we try substituting, = (sin(4(-3)+12))/(5(-3)+15) = sin(-12+12) / -15+15 = sin(0) / 0 = 0 /0 Note that 0/0 is indeterminate, and if you arrive at this answer, you use the L'hopital's rule. To use the L'hopital's rule...
*December 2, 2013*

**Physics**

You can use the formula for Uniformly Accelerated Motion (UAM): h = (v,o)t - (1/2)gt^2 Or you can use another formula, which does not use time: v,f^2 - v,o^2 = 2gd where v,f = final velocity v,o = initial velocity g = acceleration due to gravity = 9.8 m/s^2 d = distance (in ...
*December 1, 2013*

**math**

1. Yep 2. The remaining distance is is 120 - 60 = 60 miles (because the first 60 miles was already covered in 1.2 hours according to #1) Speed is distance over time, or v = d/t Substituting, 40 = 60/t t = 60/40 t = 1.5 hours 3. Yep
*December 1, 2013*

**math**

Let x = multiplier. Thus, Men = 7x Women = 5x The ratio of men to women is still 7 to 5. Since there are 440 more men than women, we can say that 7x = 5x + 440 Solving for x, 7x - 5x = 440 2x = 440 x = 220 The total men and women is 7x + 5x = 12x. Thus the total is, total = ...
*December 1, 2013*

**Physics**

Steps: 1. Get the volume of the sphere (baseball). You re given the diameter, and you can get the radius by dividing this by 2. You are also given the formula: V,sphere = 4/3 * π * r^3 Just substitute the value of radius to get V. 2. Divide the given mass by volume to get...
*December 1, 2013*

**Physics**

If you use the equation for heat released/absorbed to support your explanation, Q = m*c*(T2 - T1) where m is the mass, c is the specific heat capacity and T is the temperature. Since the only substance involved is water, c is the same for both systems. We can also say that the...
*December 1, 2013*

**Physics**

Because ice can absorb more heat from the soft drink to change its state from ice to water (latent heat), than water only. If you use the equation for heat released/absorbed, Let T2 = final temperature of ice (assume it's above 0°C, so it became water at some temp >...
*December 1, 2013*

**Math**

y = (1/2)x^2 - (3/2) -> this is a parabola differentiate: dy/dx = (1/2)*2*x - 0 dy/dx = x The line 4x - 8y = 5 has a slope of, -8y = -4x + 5 y = (1/2)x - 5/8 slope = 1/2 If this line and the tangent line of the parabola are parallel, they have the same slope: dy/dx = x 1/2...
*December 1, 2013*

**Physics**

Because it absorbs heat change its state from liquid to gas. This is called the latent heat, and it is a constant-temperature process. If the temperature changes without changing the state of a substance, it is called sensible heat. Hope this helps :3
*December 1, 2013*

**Math**

2a^2 b^3 (4a^2 + 3ab -ab) Distribute to each: 2a^2 b^3 * 4a^2 = 8a^4 b^3 2a^2 b^3 * 3ab = 6a^3 b^4 2a^2 b^3 * (-ab) = -2a^3 b^4 Adding them, 8a^4 b^3 + 6a^3 b^4 -2a^3 b^4 = 8a^4 b^3 + 4a^3 b^4 Actually either there's no answer in the choices, or there is a typo. :3
*December 1, 2013*

**algebra 1**

Um, I think I answered the same question before.. but probably I didn't explain it clearly. :3 First thing we know is that the boiling temperature of water is dependent on the altitude. We can let x as the altitude (independent variable) and y as the boiling temp (...
*December 1, 2013*

**Math**

Yes. :) The equation containing (2,4) with slope equal to -2 is y = -2x + 8.
*December 1, 2013*

**Math**

Is this the continuation of your question? :) In the previous question, we know the slope is -2, and therefore we use the point-slope formula to get the equation: y - y1 = m(x - x1) We only need the slope and one point to get the equation. Let's use the point(2,4). ...
*December 1, 2013*

**PreCal**

^No, I'm sorry don't mind my post ^^;
*December 1, 2013*

**PreCal**

2yi = 5x - 2i + 4 Divide everything by 2i to get y alone: 2yi / 21 = (5x - 2i + 4) / 2i y = (5/2i)x - 1 + 2/i Hm, I think there's a typo..
*December 1, 2013*

**Math**

There are actually infinite number of possible point B here, because if point A and point B lie on a line with a slope of -2, then two different points on that line have can be connected with a line of slope equal to -2. (I hope that's clear ^^;) But just to show how to ...
*December 1, 2013*

**Math**

1. Yep 2. Yep 3. Yep 4. Yep 5. Yep 6. Yep 7. Yep 8. Yep
*December 1, 2013*

**MATH**

Gemma: the first and second ordered pairs Tessa: the third and fourth ordered pairs I think you can observe them easily. hope this helps :3
*December 1, 2013*

**MATH :)**

They are all correct, except #5. 1.30 x 10^4 has three significant figures (1,3 and 0). hope this helps :3
*November 30, 2013*

**Chemistry**

Get first the number of moles (n) of each species. To get the moles, divide the mass by the molar mass. To get the molar mass, get a periodic table and add the individual mass of the elements in the chemical formula. H2O (water): 2*1 + 1*16 = 18 g/mol C3H8O3 (glycerine): 3*12...
*November 29, 2013*

**Chemistry**

Get first the number of moles (n) of each species. To get the moles, divide the mass by the molar mass. To get the molar mass, get a periodic table and add the individual mass of the elements in the chemical formula. H2O (water): 2*1 + 1*16 = 18 g/mol C3H8O3 (glycerine): 3*12...
*November 29, 2013*

**Math**

64 x 6^4 = 2^6 * 2^4 * 3^4 = 2^10 * 3^4 = 82944
*November 27, 2013*

**math**

Let n = number of laptops sold 5 / 9 = 20 / n 5n = 9 * 20 5n = 180 n = 36 laptops
*November 27, 2013*

**algebra 1**

You can observe that the difference between two consecutive numbers in the pattern is 9.
*November 27, 2013*

**Chemistry**

I think you lack data, and thus, this question cannot be answered.
*November 27, 2013*

**Chemistry**

Molar mass of SO2 = 64 g/mol Divide the given mass by molar mass to get the moles: n = 0.7 / 64 n = ? Now solve for n.
*November 27, 2013*

**Calculus**

Integral of x / sqrt(x-1) dx We can use substitution method. Let u = x - 1 Thus, x = u + 1 and dx = du Substituting, Integral of (u+1)/sqrt(u) du Integral of (u+1)(u^(-1/2)) du Integral of u^(1/2) + u^(-1/2) du = (2/3)*u^(3/2) + (2)*u^(1/2) + C = (2/3)*(x-1)^(3/2) + 2(x-1)^(1/...
*November 27, 2013*

**Algebra**

Just substitute x = -3 to the function: f(x) = 3x - 10 f(-3) = 3(-3) - 10 f(-3) = -9 - 10 f(-3) = -19 Hope this helps :3
*November 25, 2013*

**math**

x = (2/y^2) + 2 Place the 2 from the right side to the left side. x - 2 = 2 / y^2 Multiply both sides by y^2. (x - 2) * y^2 = (2 / y^2) * y^2 (x - 2) * y^2 = 2 Divide 2 from the right side by x - 2 to isolate all terms with y. y^2 = 2 / (x - 2) Finally, get the squareroot. y...
*November 24, 2013*

**math**

Let n = total number of students. It was said that 60% of n are girls, which is according to the problem, equal to 30. Thus, 60% * n = 30 Note that 60% is also equal to 0.6 in decimal form: 0.6 * n = 30 n = 30/0.6 n = 50 students Hope this helps :3
*November 24, 2013*

**Chemistry**

To do this, you need the the latent heat of vaporization (Lv) for water. In references, the Lv for water is 2256 J/g. The formula for the heat released of absorbed is Q = m * Lv where m = mass Lv = heat of vaporization In this case, heat is released (negative Q) because the ...
*November 24, 2013*

**Chemistry**

To do this, you need the the latent heat of vaporization (Lv) for water. In references, the Lv for water is 2256 J/g. The formula for the heat released of absorbed is Q = m * Lv where m = mass Lv = heat of vaporization In this case, heat is released (negative Q) because the ...
*November 24, 2013*

**Pre-Calc (Prove the identity)**

Recall that formula for sum in tangent: tan (a +/- b) = [tan(a) +/- tan(b)] / [1 -/+ tan(a)tan(b)] Applying this, tan^2(x/2 + π/4) = { [tan(x/2) + tan(π/4)] / [1 - tan(x/2)tan(π/4)] }^2 Note that tan(π/4) = 1, so = [(tan(x/2) + 1) / (1 - tan(x/2))]^2 = (tan...
*November 24, 2013*

**Math grade 9 and up**

x/s + y/w = 1 s/x + w/y = 4 You can use substitution. From the first equation, wx + sy = sw x = (sw - sy)/w Substitute to the second equation: s/x + w/y = 4 sy + wx = 4xy sy + (w)((sw - sy)/w) = 4((sw - sy)/w)y sy + sw - sy = 4y(sw - sy)/w sw^2 = 4swy - 4sy^2 4sy^2 - 4swy + sw...
*November 23, 2013*

**chemistry**

When NH4NO3 is dissolved in water, it dissociates into its ions, followed by a temperature drop: NH4NO3 -> NH4+ + NO3- (though it's not really that relevant though ^^;) Anyway, the heat gained or lost can be calculated using the formula Q = mc(T2 - T1) where m = mass (...
*November 23, 2013*

**pre-algebra**

Are you sure the first term is w^2 or w^3? Anyway, if it's w^3, w^3 + 4w^2 - 4w = 16 w^3 + 4w^2 - 4w - 16 = 0 w^2(w + 4) - 4(w + 4) = 0 (w^2 - 4)(w + 4) = 0 (w + 2)(w - 2)(w + 4) = 0 w = -2 w = 2 w = -4 Hope this helps :3
*November 22, 2013*

**Calculus Area between curves**

Actually your answer is correct if it's indefinite integral. :) Now that you got the answer, we can now evaluate it at the given bounds: -(1/3)(8-2x)^(3/2) , at x = -7 to 0 = -(1/3)(8-2(0))^(3/2) - [-(1/3)(8-2(-7))^(3/2)] = -(1/3)(8)^(3/2) - [-(1/3)(22)^(3/2)] = (22/3)*(22...
*November 22, 2013*

**Science**

Yes.
*November 22, 2013*

**Science**

Red has the longest wavelength, while violet has the shortest. Arranging the colors from shortest to longest wavelength: VIBGYOR
*November 22, 2013*

**cal**

f(x) = x^2 + √x We can rewrite this as: f(x) = x^2 + x^(1/2) Therefore, the first derivative is f'(x) = 2x + (1/2)*(x^(-1/2)) And the second derivative is f''(x) = 2 + (-1/4)*(x^(-3/2)) Hope this helps :3
*November 22, 2013*

**chemistry**

Let m = mass of NaCl in grams Since the given is in 22% mass/mass, 0.22 = m / 250 m = 0.22 * 250 m = 55 grams NaCl Hope this helps :3
*November 19, 2013*

**Geometry (math)**

I suggest you draw the figure, it's easier to see that way. The planes that intersect are: (1) the plane containing the cross-sectional area (one triangle) and the plane containing one lateral surface area (one rectangle); and (2) the planes containing two lateral surface ...
*November 18, 2013*

**math**

cot x - tan x = 2 cot 2x I will be solving the left side and make it look like the right side. Note that cot x = cos(x) / sin(x) and tan x = sin(x) / cos(x): cos(x) / sin(x) - sin(x) / cos(x) Combining, cos^2 (x) - sin^2 (x) / cos(x)*sin(x): Note that the numerator cos^2 (x...
*November 18, 2013*

**science**

Recall that speed is distance travelled over a certain period of time, or v = d/t Since we know the distance (5000 m) and the speed (25 m/s), we can solve for the time: 25 = 5000/t 25t = 5000 t = 5000/25 t = 200 s Hope this helps :3
*November 15, 2013*

**science**

Acceleration is the change in velocity over a certain period of time, or a = Δv / t Substituting, a = (3 m/s) / 4 s a = 0.75 m/s^2 Hope this helps :3
*November 15, 2013*

**Trigonometry**

It would be a lot easier if you draw the figure. What you would do is just a summation of Forces. Since the system is at equilibrium (forces cancel out), the sum of forces should be zero. Sum of forces at x-direction: (T1)*cos(28) - (T2)*cos(35) = 0 Sum of forces at y-...
*November 15, 2013*

**Algebra**

If you mean ln (x) = negative number, yes, they can. If you mean ln (negative number) = y, no it's not possible. If you plot ln x, the plot is asymptotic to y-axis from the right (positive values of x only), therefore the plot will never reach x equal to zero nor the ...
*November 15, 2013*

**Math**

The area of circle is given by, A = pi*(D^2)/4 where D = diameter Substituting, A = ( 3.14 * (5/2)^2 )/4 A = 4.90625 ft^2 In mixed number, this is 4 29/32 ft^2. Hope this helps :3
*November 14, 2013*

**math**

Solve for w: 100w + 10000 = 220w + 7000 100w - 220w = 7000 - 10000 -120w = -3000 w = 3000/120 w = 25 weeks hope this helps :3
*November 14, 2013*

**Geometry**

Concurrent lines are lines that intersect at a single point. Well, a figure cannot be shown here, but try to draw/imagine. For instance, in an x-y plane, you have the three concurrent lines that intersect at the origin. Now, in order to have one pair of parallel lines, the ...
*November 14, 2013*

**math**

Let x = length. Do ratio & proportion: 10 / 19 = 38 / x Cross-multiplying, 10x = 19 * 38 10x = 722 (10/10)x = 722/10 x = 72.2 in Hope this helps :3
*November 14, 2013*

**physics**

I suggest you draw the figure. Note that if you draw the figure, you'll have a scalene triangle (a triangle with no sides equal). Two of its sides are given (51 and 45), and the angle between them is 180 - 30 = 150 degrees. Since you have two given sides and an angle ...
*November 14, 2013*

**science**

Thus, it's a rational number. Note that integer and whole number are the same.
*November 14, 2013*

**physics**

If x is the displacement, note that v (velocity) = dx/dt, and a (acceleration) = dv/dt Therefore, we get the derivative of the given equation: dx/dt = 6t - 3t^2 = velocity Note that this is just the equation for velocity, and we need to maximize it. Thus, we differentiate it ...
*November 14, 2013*

**Pre-Calculus**

D = √(x^2 + 8x + 12) We can also rewrite this as D = (x^2 + 8x + 12)^(1/2) Now we have to get dD/dt. To get the derivative, recall that if x is raised to a certain constant, the derivative is x^n = n*x^(n-1) * dx We multiply the exponent to x, which is jow raised to 1 ...
*November 12, 2013*

**chemistry**

Assuming the gas is ideal, we use the ideal gas law: PV = nRT where P = pressure V = volume n = number of moles R = universal gas constant T = temperature Note that there are two different species involved, but their P and T are the same (of course, R also). Rewriting the ...
*November 12, 2013*

**chemistry-correction**

*In the second one, I mean you don't usually make solutions of defined volume and concentration in beakers, because these glasswares are not accurate in volume. (sorry about this, I misread ^^;) Also, using volumetric pipettes or simply pipettes are more accurate than ...
*November 12, 2013*

**chemistry**

The dilution formula is M1*V1 = M2*V2 Substituting, 0.02 * 100 = 0.4 * V2 V2 = 2 / 0.4 V2 = 5 mL The volume of stock solution used is correct. And we need 95 mL of water to make the target solution. One mistake here is adding water to acid. Note that you should NOT add WATER ...
*November 12, 2013*

**CHEMISTRY**

Yes it does. From the problem, it says that 50 cm^3 of AgNO3 and 50 cm^3 of HCl are mixed. Therefore, the total volume of the solution is 50 + 50 = 100 cm^3. Then an assumption is that the density of the solution is 1 g/ cm^3. We have the volume, we have the density, we can ...
*November 12, 2013*

**math**

a. I'm not sure about this ^^; sorry. b. We add the number of steps to each coordinate. The initial point is (-2,-5). Here, the x-coordinate is -2 and the y-coordinate is -5. When the drummer moved: 1 step right means plus one to the x-coordinate 3 steps up means plus ...
*November 12, 2013*

**algebra**

Let n = cost of refreshments for 26 people. We can do ratio and proportion here. For every 18 people, the cost of refreshments is $45, while for every 26 people, the cost of refreshments is $ n. Thus, 18 / 45 = 26 / n We cross-multiply: 18n = 45 * 26 18n = 1170 Divide both ...
*November 12, 2013*

**Math-Algebra**

The pressure of a gas varies directly as its temperature: P = kT Note that the temperature must be absolute (in Kelvin units). To convert, just add 273 to the degree Celsius. Substituting the given, 200 lb/in^2 = k (65.5 + 273) k = 200 / 338.5 k = 0.5908 Now that we know the k...
*November 11, 2013*

**Math - Algebra**

Are you sure it's 81.5 N on the surface of the moon? #1. Anyway, what we'll do is first get the mass of the man. Note that mass is constant, and in physics, it is different from the term 'weight' (though in other cases, they are interchangeable, like in ...
*November 11, 2013*

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