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The power ($P$) of an engine is measured in horsepower using the formula: $$P = \frac{R \times T}{5252}$$ where $R$ is the engine speed measured in revolutions per minute (RPM) and $T$ is the torque measured in appropriate units - Leaving Cert Mathematics - Question 8 - 2019

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Question 8

The-power-($P$)-of-an-engine-is-measured-in-horsepower-using-the-formula:--$$P-=-\frac{R-\times-T}{5252}$$--where-$R$-is-the-engine-speed-measured-in-revolutions-per-minute-(RPM)-and-$T$-is-the-torque-measured-in-appropriate-units-Leaving Cert Mathematics-Question 8-2019.png

The power ($P$) of an engine is measured in horsepower using the formula: $$P = \frac{R \times T}{5252}$$ where $R$ is the engine speed measured in revolutions per... show full transcript

Worked Solution & Example Answer:The power ($P$) of an engine is measured in horsepower using the formula: $$P = \frac{R \times T}{5252}$$ where $R$ is the engine speed measured in revolutions per minute (RPM) and $T$ is the torque measured in appropriate units - Leaving Cert Mathematics - Question 8 - 2019

Step 1

Find the power of an engine that generates 480 units of torque at 2500 RPM.

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Answer

To find the power, substitute the values into the formula:

P=480×25005252P = \frac{480 \times 2500}{5252}

Calculating this gives:

P=12000005252228.48P = \frac{1200000}{5252} \approx 228.48

Rounding to the nearest whole number, the power is 228 horsepower.

Step 2

Rearrange the formula to write $R$ in terms of $P$ and $T$.

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Answer

Starting from the original formula:

P=R×T5252P = \frac{R \times T}{5252}

Multiply both sides by 5252:

5252P=R×T5252P = R \times T

Now, divide both sides by TT:

R=5252PTR = \frac{5252P}{T}

Step 3

Complete the table below to show the company’s loss/profit for each of the first six months of trading.

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Answer

MonthProfit (€)
1-4000
2-3750
3-3500
4-3250
5-3000
6-2750

Step 4

Show that the profit the company makes in month $n$ is given by the formula.

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Answer

Given the initial loss of €4000 and reducing the loss by €250 each month, the profit can be expressed as:

Tn=4000+(n1)250T_n = -4000 + (n-1)250

Simplifying this results in:

Tn=250n4250T_n = 250n - 4250

Step 5

What profit does the company make in January 2018 (i.e. month 25)?

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Answer

To find the profit in month 25, substitute n=25n = 25 into the profit formula:

T25=250(25)4250T_{25} = 250(25) - 4250

Calculating this gives:

T25=62504250=2000T_{25} = 6250 - 4250 = 2000 €

Step 6

Find the month in which the company breaks even (i.e. €0 profit).

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Answer

To find when the company breaks even, set the profit formula to zero:

250n4250=0250n - 4250 = 0

Solving for nn gives:

250n=4250250n = 4250

Thus,

n=4250250=17n = \frac{4250}{250} = 17

The company breaks even in month 17.

Step 7

Find $S_n$, the general term for the total profit of the company after $n$ months.

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Answer

The total profit SnS_n after nn months can be calculated as:

Sn=n2[4000+(n1)250]S_n = \frac{n}{2}[-4000 + (n - 1)250]

This simplifies to:

Sn=n2[8000+250n]S_n = \frac{n}{2}[-8000 + 250n]

Step 8

Hence, find the total profit of the company at the end of January 2019 (i.e. month 37).

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Answer

To find the total profit at the end of month 37:

S37=372[8000+250×37]S_{37} = \frac{37}{2}[-8000 + 250 \times 37]

Calculating inside the brackets first:

S37=372[8000+9250]=372[1250]S_{37} = \frac{37}{2}[-8000 + 9250] = \frac{37}{2}[1250]

Thus,

S37=37×625=23125S_{37} = 37 \times 625 = 23125 €

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