# Pre algebra questions and answers

Recent questions in Pre-Algebra
Ratios, rates, proportions

### A piston–cylinder device initially contains $$\displaystyle{0.07}{m}^{{{3}}}$$ of nitrogen gas at 130 kPa and $$\displaystyle{180}^{{\circ}}$$. The nitrogen is now expanded to a pressure of 80 kPa polytropically with a polytropic exponent whose value is equal to the specific heat ratio (called isentropic expansion). Determine the final temperature and the boundary work done during this process.

Ratios, rates, proportions

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### A roof has a 0.4-inch layer of ice on it from a previous storm. Another ice storm begins to deposit ice at a rate of 0.26 inches per hour. a) Find a formula for a linear function f that models the thickness of the ice on the roof x hours after the second ice storm started. b) How thick is the ice after 3.5 hours? a) $$\displaystyle{f{{\left({x}\right)}}}=$$___ b) The ice is ___ inches thick after 3.5 hours.

Ratios, rates, proportions

### The time in hours taken by a truck to travel 144 miles is 3 Calculate time in hours taken by a truck to travel 1,200 miles:

Ratios, rates, proportions

### What’s the difference between a ratio and a proportion?

Ratios, rates, proportions

### A. What is an equation? B. Explain the difference between a linear and a quadratic equation in terms of degree and solution. C. Givea concise definition of the following: 1. Rate 2 Ratio 3. Proportion

Ratios, rates, proportions

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### In macroeconomic theory, total consumption expenditure on goods and services, C, is assume to be a linear function of national income, I. The table gives the values of C and I for 2004 and 2009 in country A(in billions of dollars). a. Find the formula for C as a function of 1. b. The slope of the linear function is called the marginal propensity to consume. What is the marginal propensity to consume for country A from 2004-2009? a. FInd the formula for C as a function of I. $$\displaystyle{C}=?$$ $$\begin{array}{|c|c|} \hline \text{Year}&2004&2013 \\ \hline \text{Total consumption (C)}&8,289&10,086\\ \hline \text{National income(f)}&9,938&12,027\\ \hline \end{array}$$

Ratios, rates, proportions

### The Otto-cycle engine in a Mercedes-Benz SLK230 has a compression ratio of 8.8. a) What is the ideal efficiency of the engine? Use $$\displaystyle\gamma={1.40}$$ b) The engine in a Dodge Viper GT2 has a slightly higher compression ratio of 9.6. How much increase in the ideal efficiency results from this increase in the compression ratio?

Ratios, rates, proportions