?

the population mean is 200cm for the unknown amount of rods in the population

the pop sd is 4cm

the ONE sample of 4 rods is randomly taken from the population, and the one sample of 8 rods is taken from the population, which one should be closer to the population mean and standard deviation?

I know the central limit theorem (pop sd /sqrt n), but isn't this the standard deviation of the sample means, not the standard deviation of one sample itself?

Any help on explaining this would be great

I need some help on these questions

9x10^4L of rainwater with an average hydrogen ion concentration of 1x10^-4g/L was collected and stored in a galvanised iron tank. After several months the pH of the water was found to be 7. Assuming the zinc was the only material in contact with the water, calculate the

a) mass of zinc that would of dissolved

b) the concentration of zinc ion, in mol/L, in the rainwater

Sweat is a solution containing mainly sodium,potassium, chloride ions. The concentration of hydrogen ions in sweat= 1x10^-5g/L. Calculate the mass of solid calcium hydroxide required to neutralise 10mL of sweat

a) Calculate the concentration in mol/L, of a sodium carbonate solution produced from 250g sodium carbonate 10 water dissolved into 2L of water to produce 2.1L of solution

b) If sodium carbonate neutralized hydrochloric acid, calculate the mass of sodium chloride produced if all of the 2.1L sodium carbonate solution reacted with the acid

To determine the purity of limestone, mostly calcium carbonate, an analyst measured the mass of a small sample of limestone to be 2.59g. He placed enough HCl into a beaker to completely dissolve the limestone sample. The beaker and acid had a mass of 110.61g. He then placed the limestone sample into the acid and allowed it to completely dissolve. After the reaction was completed the mass of the beaker and it s contents was found to be 112.22g. Calculate the percentage purity of the limestone.

Any help is great, thx

I need some help on these questions

9x10^4L of rainwater with an average hydrogen ion concentration of 1x10^-4g/L was collected and stored in a galvanised iron tank. After several months the pH of the water was found to be 7. Assuming the zinc was the only material in contact with the water, calculate the

a) mass of zinc that would of dissolved

b) the concentration of zinc ion, in mol/L, in the rainwater

Sweat is a solution containing mainly sodium,potassium, chloride ions. The concentration of hydrogen ions in sweat= 1x10^-5g/L. Calculate the mass of solid calcium hydroxide required to neutralise 10mL of sweat

a) Calculate the concentration in mol/L, of a sodium carbonate solution produced from 250g sodium carbonate 10 water dissolved into 2L of water to produce 2.1L of solution

b) If sodium carbonate neutralized hydrochloric acid, calculate the mass of sodium chloride produced if all of the 2.1L sodium carbonate solution reacted with the acid

To determine the purity of limestone, mostly calcium carbonate, an analyst measured the mass of a small sample of limestone to be 2.59g. He placed enough HCl into a beaker to completely dissolve the limestone sample. The beaker and acid had a mass of 110.61g. He then placed the limestone sample into the acid and allowed it to completely dissolve. After the reaction was completed the mass of the beaker and it s contents was found to be 112.22g. Calculate the percentage purity of the limestone.

Any help is great, thx

I know how to do most of acid base questions but i'm having trouble with these; in the problems use pH=-log(H+)

200mL of a 0.1mol/L HCl solution is added to 198mL of a 0.1mol/L NaOH solution. Calculate the hydrogen ion and hydroxide ion concentrations in the resulting solution.

0.25g of sodium hydroxide are added to 115mL of a nitric acid solution of pH 1.50. Determine the pH of the resulting solution. Assume volume does not change on adding the solid.

10.6g of anhydrous sodium carbonate are dissolved in 560mL of a 0.54mol/L HCl solution

a) Calculate the pH of the final solution, assuming volume does not change on adding the solid

b) What volume of water must be added to give a solution having pH 1

Any help is great, thx

How do u do these questions?

The point (1,e) lies on the graph e^x. State the transformations made upon y=e^x for the function to become y=-e^(2x-3)+2, and give the exact co ordinates of the transformation of the point (1,e)

And if a function is transformed to y=e^(3x+3) from y=e^x does this mean that it has done a dilation of 1/3 to the x axis and has translated 1 unit left?

Any help would be great, thx

I need help with finding out these equations

Magnesium is burnt in air (and reacts with both the oxygen and nitrogen of the air)

Sodium sulfide solution reacting with sulfuric acid

Thx

How do you solve these questions, any ideas would be great

1. ABCD is a regular tetrahedron of edge length 10cm. Calculate, correct to two dps, the size of the angle between the face ABC and the face BCD

2. A ship travelling due North at a constant speed of 18km/h. At 8.00 pm a lighthouse is observed at a bearing 025 degrees. One hour later the lighthouse is observed at a bearing of 040 degrees.

a. calculate to the nearest tenth of a kilometre the distance of the lighthouse from the ship at 9.00 pm

b. Calculate, correct to the nearest minute, the time when the ship will be due west of the lighthouse

Thx

Any info is useful, also info on how this was implemented in different countries, and what situations arose due to this relief Thx :-)

Discuss the ways in which The Book Thief examines the power of words

Any ideas, points , examples and explanations, responses relating to the question are useful

If you could find any situation where the power of words is shown or quotes that would be great too!!

Thx!

1. An open cardboard box is to be made by cutting squares of side x cm from each corner of a square of card of side 60 cm and folding the "resulting" flaps up to form the box. Find the value of x that will give the box the maximum volume

2. A body is projected from an origin o and moves in a straight line such that its displacement from 0, t seconds after projection is s metres where s=(t^3)/3-(6t^2)+50t. The velocity of the body is given by ds/dt.

For what value of t is the body moving with the minimum velocity and how far from O is the body at that time?

3. The curve y=ax^2 + b passes through the points A (3,39) and B (-2,c). The tangent to the curve at A is parallel to the line y-30x+7=0

Find a,b,c and the equation of the tangent to the curve at B

In this equation 2HCl+Na2CO3=2NaCl+H2O+CO2, what is the limiting reagent and how do do you find the amount of co2 produced, given that 20ml of 2.0M Hcl is used and 5g of Na2CO3 is used?

In this equation 2HCl+Na2CO3=2NaCl+H2O+CO2, what is the limiting reagent and how do do you find the amount of co2 produced, given that 20ml of 2.0M Hcl is used and 5g of Na2CO3 is used?

How many moles of acid do you have if you have 20ml of 2.0M HCl?

in the equation i'm relating this to , will the 2Hcl is this equation make a difference to the amount of moles of acid

2HCl+Na2CO3=2NaCl+H2+CO2

How many moles of acid do you have if you have 20ml of 2.0M HCl?

is a core i3 330, 4gb ram, 2,13 ghz, 1gb graphics card, 500gb hdd, windows 7 home premium good enough to play any game at all.

If not could you give me examples of games that would not work?

My computer's text on the desktop and on the browser- everywhere has gone fuzzy. It's only just readable. When i change on off cleartype it doesn't help. My current resolution is 1024x768, and on all other resolutions the text is fine. But i can't use the other resolutions because the browser doesn't fit on the screen. How do i fix this?

Ps this started when my brother played a game and then closed it and then text was all fuzzy. I tried doing what he did again but the text only got worse, like it was overlapping.

Any suggestions.

Let ABC be a triangle. Two straight lines which are parallel to the side AC divide the triangle into three figures of equal area. in what parts is the side AB divided by the lines, if AB=10cm?

Let 5a+12b and 12a+5b be the side lengths of a right angled triangle and 13a+kb be the hypotenuse, where a,b and k are positive integers. Find the smallest possible value of k and the smallest values of a and b for that k

Eleven people, 7 men and 4 women, successfully completed their study at the School of Astronautics. a team of 6 people needs to be selected from them for the next intergalactic travel. In how many ways can 6 astronauts be selected, if at least 2 women and 3 men must be in the team?

Prove that a number 10^3n+1, where n is a positive integer, cannot be represented as the sum of two cubes of positive integers.