# Posts by Grace

Total # Posts: 648

**Math**

If a letter is chosen at random from the word PRESEVERANCE,what is the probability that the letter choosen is E?

*May 9, 2012*

**statistics**

On an exam whose scores followed a normal distribution, a student's z-score was +2. What percentage of students scored better than he did? (Use the 68-95-99.7 Rule.)

*April 25, 2012*

**noun**

if two dices are tossed together, the probability that the product will be less or equal to 18 what?

*April 24, 2012*

**Chemistry**

Are hybridized orbitals used to explain the fact that the four bonds in methane are equivalent? If not, what is?

*April 16, 2012*

**Chemistry**

The pH of a 0.100 M solution of an aqueous weak acid (HA) is 4.00. What would the Ka for the weak acid be?

*April 16, 2012*

**physics**

tommy builds a human sling shot that has an elastic constant of 4000 N/m. He puts his little sister in it and pulls it back for 5 meters. How much energy does his 25 kg sister have as she leaves the sling shot and how fast is she flying?

*March 27, 2012*

**maths**

Please I want to know how many litres make a metric tone.

*March 25, 2012*

**STATISTICS**

.868

*March 19, 2012*

**physics**

How would one plug the gravitational constant into an equation? To be honest, I'm having a hard time with the idea of the gravitational constant in general, but I need to solve an equation for the circular velocity of a galaxy. I know I need to multiply the gravitational ...

*March 8, 2012*

**6th Grade Math**

Simon went to the store to buy new school supplies. Simon spent 1/4 of his money on pencils and paper and 1/2 of his money on a backpack. If Simon has $12.50 leftover, how much did the backpack cost?

*March 4, 2012*

**Math**

There are 24 students in Mrs.Smith's 1st block class. 1/4 of the class passed the math test with an A. 12 students in the class passed the math test with a B. What percent of the students in the class passed the test?

*March 1, 2012*

**Math**

There are 24 students in Mrs.Smith's 1st block class. 1/4 of the class passed the math test with an A. 12 students in the class passed the math test with a B. What percent of the students in the class passed the test? ****** This is how I slove the problem, but I stuck in ...

*March 1, 2012*

**physical science**

120ml of a solution whose concentration is 30g/ml was diluted with distilled water by raising its volume to 160cm3. Calculate the concentration of the new solution.

*February 25, 2012*

**Algebra 2**

did you ever get this answer?

*February 21, 2012*

**statistics**

0.215

*February 17, 2012*

**chemistry**

Pls promise where is the valuefor r in that question

*February 17, 2012*

**math**

I have a question. I think I'm wrong, so I want to ask if it's right. If I do 3/4 x 1 5/6 x 7/4 x (-2 3/8) would the answer be negative?

*February 6, 2012*

**Math**

Given h(r) = 1/(r + 2), find: h(x^2) + 1 Thank You

*February 4, 2012*

**math**

the chef at a restaurant bought 37 pounds of salad for $46.25. how much did she pay for 1 pound of salad

*January 30, 2012*

**chemistry**

9.5 g Butane + 34.0 g Oxygen = 43.5 Then 43.5 - 28.7 g CO2 = 14.8 That is the answer: 14.8 g

*January 22, 2012*

**Precalc**

An ellipse has this Cartesian equation: ((x-2)/5)^2 + ((y-4)/3)^2 = 1 Find the focal radius Find the eccentricity Write the parametric equations for the ellipse Transform into the form, Ax^2 + By^2 + Cx + Dy + E = 0

*January 20, 2012*

**Precalc**

A hyperbola has this Cartesian equation: -((x-2)/5)^2 + ((y+1)/3)^2 = 1 A. Find direction in which it opens. Horizontal? B. Find the coordinates of the center. I think it's (-2,1) or (1,-2)? C. Find the slopes of the asymptotes: m=+- ?

*January 20, 2012*

**Precalc**

The figure shows the pre-image and first iteration for a set of transformations. If the iterations are carried on infinitely, the resulting fractal figure will have dimension given by Dimension=(LogN)/Log(1/r) It tells me to find N and r... What should I be looking for on the ...

*January 19, 2012*

**Precalc**

Thank you so so so much! I've been stuck on this for hours!

*January 19, 2012*

**Precalc**

The figure shows a 10 x 10 square centered at the origin. The darker-shaded square is the image of this square, dilated by a factor of 0.8 and rotated about the origin by exactly the number of degrees, , so that its corners touch the sides of the parent square. The corners of ...

*January 19, 2012*

**4thGrade Math**

11/15 feet long per piece. Or 8.8 inches.

*January 19, 2012*

**Precalc**

For this matrice, [[0.9cos(-30), 0.9cos(60), 2] [0.9sin(30), 0.9sin(60), 4] [0, 0, 1]] What is the rotation (in degrees) and is it clockwise or counterclockwise? I think it's 30 degrees clockwise...Is that right?

*January 19, 2012*

**Precalc**

I think it's [[2,4,6,4] [4,5,4,1] [1,1,1,1]] Is that correct?

*January 19, 2012*

**Precalc**

Write a 3 x 4 pre-image matrix for a kite with the points (2,4) (4,5) (6,4) and (4,1)

*January 19, 2012*

**Precalc**

I have: A. vector n= 3*vector i + 2*vector j + 5* vector k B. vector v= 7*vector i + 10*vector j + vector k C. 52.46 degrees And I'm not quite sure for D...

*January 18, 2012*

**Precalc**

Given the plane 3x+2y+5z=54 and the points P0(6, 8, 4)[on plane] and P1(13, 18, 5) [not on plane] A. Find vector n, a vector normal to the plane B. Find vector v from P0 to P1 C. Find the angle between vector n and vector v D. Find p, the scalar projection of vector v on ...

*January 18, 2012*

**Precalc**

Is it just ((6/11), (9/11), (2/11)) ?

*January 18, 2012*

**Precalc**

Yeah, sorry about that. There's a diagram to it and I wasn't sure how else to explain it.

*January 18, 2012*

**Precalc**

A line in space has the vector equation shown here. Fill in the blanks to find the position vector to the fixed point on the line that appears in the equation: vector r=(5+(6/11)d)vector i + (3+(9/11)d)vector j + (7+(2/11)d)vector k vector v= _____ vector i + _____ vector j + ...

*January 18, 2012*

**Precalc**

Ah. Alright, I think I understand.

*January 18, 2012*

**Precalc**

Thanks so much!

*January 18, 2012*

**Precalc**

I wish I could say that's why I don't understand this problem. But sadly, I still don't get it. Haha.

*January 18, 2012*

**Precalc**

In the problem before it says r(x)= (x^5 - c^5)/(x-c) Maybe it's referring to that? Does that help?

*January 18, 2012*

**Precalc**

By appropriate calculations, show that: lim r(x)=5c^4 (x->c)

*January 18, 2012*

**Precalc**

If α, β, and γ are direction angles for a vector in three dimensions and cos α = 0.6 and cos β = 0.7, find cos γ

*January 17, 2012*

**Precalc**

Suppose vector a is 3 units long, the magnitude of vector b is 1 units and cos (θ) = -0.3, where θ is the angle between the two vectors when they are placed tail-to-tail. What does the inner product of vector a and vector b equal?

*January 16, 2012*

**world history**

The dominant political philosophy in the Qin Dynasty was legalism.

*January 7, 2012*

**Precalc**

At the point were a line intersects a plane [with the equation (24x+32y+40z=480) and three points of A(5, 10, 1), B(6, 3, 6), and C(12, 1, 4)], the vector i-, vector j-, and vector k-coefficients of the line equal the corresponding values of x, y, and z for the plane. By ...

*January 7, 2012*

**Precalc**

Thank you (:

*January 7, 2012*

**Precalc**

Assume that points A(5, 10, 1), B(6, 3, 6), and C(12, 1, 4) are on a plane. Find vector AB and vector AC.

*January 7, 2012*

**Precalc**

Assume that points A(5, 10, 1), B(6, 3, 6), and C(12, 1, 4) are on a plane. Find vector AB and vector AC.

*January 7, 2012*

**statistics**

In 2005, about 233 million people in the United States were aged 14 or older. They consumed, on average, 2.23 gallons of alcohol per person. use scientific notation to estimate the total number of gallons of alcohol consumed by this age group.

*November 23, 2011*

**Science**

What do polar bears and automobiles have in common?

*November 15, 2011*

**Math**

Solve: ((10)/(x^2-3x+45))=x+1

*November 13, 2011*

**Living environment**

diffusion

*October 27, 2011*

**Algebra 2 Problem**

You own a computer store selling two types of laser printers. The first type,A, costs $141 and you make a $45 profit on each one. The second type,B, costs $110 and you make a $35 profit on each one. You expect to sell at least 100 laser printers this month and you need to make...

*October 27, 2011*

**Physical Science**

a 30 kg girl and a 25 kg boy face each other on a friction-free blades. The girl pushes the boy, who moves away at a speed of 1.0 m/s. The girls speed is __________m/s

*October 25, 2011*

**environmental science**

describe and compare total resource use per capita in developed and developing countries

*October 21, 2011*

**math**

in the month of May, ronald earned $4.36 in interest on his saving account. if his interest rate is 0.2%, how much money was in his account during the month?

*October 18, 2011*

**Biology**

Which internal organs of the fetal pig appear to have the greatest amounts of blood supplied to them? Why does this make sense?

*October 17, 2011*

**Biology**

Is the pancreas an exocrine or endocrine gland? Indicate the anatomical evidence on your fetal pig. What are its contributions to digestion and where are they added to the digestive tract?

*October 17, 2011*

**earth**

Which process could lead directly to the formation of pumice rock?

*October 2, 2011*

**chemistry thank you**

concentrated sulfuric acid has a density of 1.84 g/ml. calculate the mass in grams of 1.00 liter of this acid

*September 27, 2011*

**physics!**

The driver of a 1560 kg automobile traveling at 24 m/s on a leve, paved road hits the brakes to stop for a red light. determine the distance needed to stop the car if the coefficient of friction between the car tires and the road is .80 -one of the steps required of me to ...

*September 23, 2011*

**algebra**

how to figure 75% of 620

*September 21, 2011*

**biology**

explain why the synthesis of proteins, DNA and RNA requires energy. thanks :)

*September 21, 2011*

**biology**

thanks again!

*September 21, 2011*

**biology**

outline why energy is needed for each of these processes: a. the transport of sucrose in a plant b the transmission of an action potential along a nerve axon c. the selective reabsorption of glucose from a kidney nephron I'm not exactly sure how I'm supposed to answer ...

*September 21, 2011*

**Biology**

What are two major flaws in the Phylogenetic Tree System?

*September 20, 2011*

**chemistry**

thanks

*September 15, 2011*

**chemistry**

in emission spectrum which one has a highest frequency and highest energy is it blue red or violet? which one is the lowest?

*September 15, 2011*

**math**

what will i answer if the question is " identify the symmetry" is it even/odd FUNCTION or Even/odd SYMMETRY?

*September 15, 2011*

**chemistry**

yes, it's all about emission spectrum..

*September 15, 2011*

**chemistry**

does elements with low energy have high frequency?

*September 15, 2011*

**Chemistry**

What is the Wavelength( in nm) of the least energetic spectral line in the infrared series of the H atom? I don't understand how to find the least energetic spectral line?

*September 10, 2011*

**physics**

A man pushing a mop across a floor causes the map to undergo two displacements. The first has a magnitude of 200 cm and makes an angle of 120° with the positive x axis. The resultant displacement has a magnitude of 240 cm and is directed at an angle of 60.0° to the ...

*September 10, 2011*

**Chemistry**

Covalent bonds in a molecule absorb radiation in the IR region and vibrate at characteristic frequencies. a) The C---O bond absorbs radiation of wavelength 9.6um. What frequency (in s-1) corresponds to that wavelength? b) The H---Cl bond has a frequency of vibration of 8....

*September 8, 2011*

**Chemistry**

I don't understand that process, since the answer for the meters is supposed to be 316m

*September 7, 2011*

**Chemistry**

An AM station broadcasts rock music at "950 on your radio dial" Units for AM frequencies are given in kilhertz(kHz). Find the wavelength of the station's radio waves in meters, nanometers, and angstroms.

*September 7, 2011*

**Chemisty**

Calculate the energy in radiation of wavelength 550 nm carried by 1) one photon 2) 1 mol of photons

*September 6, 2011*

**Chemisty**

Calculate the energy in radiation of wavelength 550 nm carried by 1) one photon 2) 1 mol of photons

*September 6, 2011*

**Math**

Like decimals, charts, fractions, estimating. At least that is what I had in 5th.

*September 4, 2011*

**SAT math**

If five distinct lines lie in a plane, then at most how many distinct points can lie on two or more of these lines? 6 7 8 9 10.

*August 19, 2011*

**algebra**

TGIF. Chris and Terry have been trying to live within their budget but miss going out to dinner on Friday nights. They decide not to spend any nickels or quarters they receive as change for a month and save these in a jar. At the end of the second week they have a total of 165...

*July 17, 2011*

**math**

Write the equation of the line satisfying the given condition. Parallel to y = (2/3)x +1 and passing through the point (0, -3). (Hint: Parallel lines have the same slope

*July 17, 2011*

**algebra**

Write the equation of the line satisfying the given condition. Perpendicular to y = 4x + 2 and passing through the point (0, -4) (Hint: Slopes of non-vertical perpendicular lines are negative reciprocal of each other.)

*July 17, 2011*

**algebra**

Solve the inequality algebraically. Graph your solution on a number line.

*July 17, 2011*

**math**

Suburban Population. The following charts show the populations for two suburbs from 1980 to 1990, where x = 0 correspond to 1980, x = 2 correspond to 1982, and so on. Year x Suburb 1 y Year x Suburb 2 y 0 12,690 0 23,112 2 12,071 2 23,893 4 13,463 4 24,674 6 13,867 6 25,455 8 ...

*July 17, 2011*

**math**

The average (arithmetic mean) of x and y is m, where m does not equal to 0. What is the average (arithmetic mean) of x, y, and z? a.)m b.)4/3m c.)3/2m d.)5/3m e.)2m

*July 10, 2011*

**math**

A flat stone is thrown horizontally across a frozen lake. If the stone decelerates at 2.5 meter per second squared, what is the coefficient of friction between the stone and the ice?take g equals 10 meter per second

*June 18, 2011*

**Science (Chemistry)**

The Average density of Earth is 5.52g/cm^3. What is its density in a. kg/m^3 b. lb/ft^3. Please help me set up these equations. Thank you!

*June 13, 2011*

**physics**

What is force of attraction between two students of mass 20kg,10meters apart?

*June 5, 2011*

**physics**

What is force of attraction between two students of mass 20kg,10meters apart?

*June 5, 2011*

**science**

i need 3 examples of supension. any suggestions?

*May 11, 2011*

**maths**

Oh sorry! Thanks

*May 8, 2011*

**maths**

The mass of a particular substance is known to grow exponentially at a rate of 0.5% per hour. Its initial mass was 25 grams and, after t hours, it weighed 31 grams. The equation modelling this growth is 25×1.005 t = 31. Use the method of ...

*May 8, 2011*

**chemistry**

Which of the following statements are true? Fusion reactions result in nuclei with higher Z. To keep a nuclear power plant going, a chain reaction must be maintained. Nuclear fusion produces no long-lived radioactive by-products. The Sun is a nuclear fusion reactor.

*April 14, 2011*

**Algebra 1**

What is 1/9+1/y=4/y

*April 5, 2011*

**physics**

A car is travelling at 42.4 km/h on a flat highway. The acceleration of gravity is 9.81 m/s^2. If the coefficient of friction between the road and the tires on a rainy day is 0.125 what is the minimum distance for the car to stop? Answer is metres

*April 2, 2011*

**maths**

find in implicit form, the general solution of the differential equation dy/dx = 2(e^x-e^-x)/y^2(e^x+e^-x)^4

*March 24, 2011*

**chemistry**

Why sodium oxide is a solid at room temperature whereas sulfur trioxide is a low boiling point liquid?

*March 12, 2011*

**Chemistry**

The boiling ponit of phophine is -85 oC, whilst of ammonia in the same group is -33.5 oC, how can we account for this difference in BP?

*March 12, 2011*

**chemistry**

sorry if that was confusing

*March 2, 2011*

**not really sure**

What is the mass of a mole of Sodium Carbonate?

*March 2, 2011*

**Life orientation**

Which two labour laws protect the employee against discrimination in the work place?

*February 21, 2011*