# Posts by Helga

Total # Posts: 28

**maths**

The cost of a gift is shared amongst 3 kids. Keith paid €480 more than jack. Keith paid €220 more than the total amount paid by Jack and tim. Jack paid 80 more than tim. How much did the present cost?

**business studies**

can you please help me. issues that affect ethical and professional behaviour of the business

**Chemistry**

Can you put the figures into the equation for me, because I do not quite understand this?

**Chemistry**

One of the reactions that occurs in a blast furnace, in which iron ore is converted to cast iron, is Fe2O3 + 3CO → 2Fe + 3CO2 Suppose that 1.59 × 103 kg of Fe is obtained from a 2.54 × 103 kg sample of Fe2O3. Assuming that the reaction goes to completion, ...

**Math**

8 people are going to sit on 6 chairs. Two of them John and Kelly can't sit next to each other. How many ways can you put the people to seats? The answer is 10080, but I can't figure out how to calculate it.

**calculus**

Consider the function f(x)=x^n for positive integer values of n. (a) For what values of n does the function have a relative minimum at the origin? (b) For what values of n does the function have a point of inflection at the origin?

**Chemistry**

In the titration of 20.00 mL of 0.175 M NaOH, calculate the number of milliliters of 0.200 M HCl that must be added to reach a pH of 12,55. I know the answer is 11,9 mL but I don't know how to calculate it.

**research**

A quantitative analysis method which aggregates a number of (similar) individual studies into a large data set from which to compute an over all “effect size” (based on similar study procedures and treatments) is commonly known as…?

**Chemistry**

when 20 ml of a .10 M silver nitrate solution is mixed with 25 ml of a 0.080 M solution of sodium sulfide, producing a precipitate of silver sulfide, what is the final concentration of sulfide ion?

**Chemistry**

The oxides of Group 2A metals (symbolized by M here) react with carbon dioxide according to the following reaction: MO(s) + CO2(g) MCO3(s) A 2.85-g sample containing only MgO and CuO is placed in a 3.00-L container. The container is filled with CO2 to a ...

**Chemistry**

A bicycle tire is filled with air to a pressure of 610 kPa at a temperature of 19 oC. Riding the bike on asphalt on a hot day increases the temperature of the tire to 58 oC. The volume of the tire increases by 4.0%. What is the new pressure in the bicycle tire?

**Algebra**

Is there a more elegant solution than trial and error?

**Algebra**

How do I calculate 4^n=1/(2(n-n^2))? Thanks.

**Binomial expansion**

The coefficient of x^2 in the expansion of (4-3x)^n as a series of ascending powers of x is -9/64. Show that n satisfies the equation 4^(n+1)=2/[n(1-n)] and hence verify that n=1/2. I can do the first part of the problem: 4^n*3^2*n(n-1)/2!*2^4=-3^2/2^6 4*4^n*n(n-1)=-2 4^(n+1)*...

**Newton's Law of Cooling**

Oh, I see. So to make an estimate you'd have to make an assumption of ambient temperature, right? Assuming constant ambient temperature of 10°C, the time of death could be estimated to be at around 4.45 (i.e 4 to 4 1/2) hours before discovery. Is that correct?

**Newton's Law of Cooling**

Shame about your computer. Don't want to die wondering ;)

**Newton's Law of Cooling**

You are a forensic doctor called to a murder scene. When the victim was discovered, the body temperature was measured and found to be 20°C. You arrive one hour later and find the body temperature at that time to be 18°C. Assuming that the ambient temperature remained ...

**Calculus**

A container in the form of a right circular cone of height 16 cm and base radius 4 cm is held vertex downward and filled with liquid. If the liquid leaks out from the vertex at a rate of 4 cm^3/s, find the rate of change of the depth of the liquid in the cone when half of the ...

**Calculus**

A right circular cone has a constant volume. The height h and the base radius r can both vary. Find the rate at which h is changing with respect to r at the instant when r and h are equal.

**Pre-Calculus**

It may look lame but I can't work out how to solve (-9) sqrt(4-x^2) = 4x + 5sqrt2. I need some guidance, please.

**Calculus**

Differentiate x^2*y^2 = (y+1)/(x+1) in terms of x and y. PS My answer is unfortunately at odds with that provided by the authors of the book (i.e. -y (y+1) (3x+2) all over x (x+1) (y+2), and I don't know whether it's a misprint or my method is wrong.

**Calculus**

If f(x) = x ln(1+x) estimate the value of ln (2.1) given that ln2 = 0.6931.

**accounting**

Seurities Fair Value Adjustment (Trading) Account Securities Fair Value Adjustment (Trading) + (Gain) - (Loss) 25,000 Ending Balance 12/31/2009 Adjusting entry on 12/31/2010 35,000 Ending Balance on 12/31/2010 10,000 40,000 Adjusting entry on 12/31/2011 30,000 Ending Balance ...

**Westen Civ.**

Which governmental bodies are responsible for making laws in the United States? How does a written law protect American democracy?

**History on WW1**

How did President Wilson use Russia's democratic revolution to gain support for the war?

**stat math**

Stat hw question help me please? In a high profile murder case a sample of the general public's opinions concerning the guilt or innocence of the defendant is taken. A sample of n=100 males results in 62% of the respondents beliving that the defendant is guilty, while a ...

**math**

A random sample of the houses in a particular city is selected and each of the houses in a particular city is selected and each of the house's level of radon gas is measured. The values collected are given in the table below in parts per million (ppm). 4 8 13 6 7 3 9 8 11 ...

**statistics**

what are the mean and standard deviation of a sampling distribution consisting of samples of size 16? these sameples were drawn from a population whose mean is 25 and who standard deviation is 5. a. 25 and 1.25 b. 5 and 5 c. 25 and 5 d. 5 and 1.25 e. 25 and square root of 5 ...