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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 m... 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. Give your answer correct to the nearest whole number.

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Answer

To find the power, we 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 with the original formula:

P=R×T5252P = \frac{R \times T}{5252}

We rearrange it to solve for R:

R=P×5252TR = \frac{P \times 5252}{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

Month123456
Profit (€)-4000-3750-3500-3250-3000-2750

Step 4

Show that the profit the company makes in month n is given by the formula Tn = 250n - 4250.

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Answer

The profit for month n can be calculated as follows:

Initial loss of €4000 reduces by €250 each month, so:

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

Simplifying gives:

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 = 25 into the formula:

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

Calculating this gives:

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

Thus, the company makes a profit of €2000 in January 2018.

Step 6

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

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Answer

Setting the profit formula to zero:

0=250n42500 = 250n - 4250

Solving for n gives:

250n=4250n=17250n = 4250 \Rightarrow n = 17

Thus, the company breaks even in month 17.

Step 7

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

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Answer

The total profit after n months can be found by summing the profit for each month:

Sn=k=1nTk=k=1n(250k4250)S_n = \sum_{k=1}^{n} T_k = \sum_{k=1}^{n} (250k - 4250)

This simplifies to:

Sn=250(n(n+1)2)4250n=250n(n+1)24250nS_n = 250 \left( \frac{n(n + 1)}{2} \right) - 4250n = \frac{250n(n + 1)}{2} - 4250n

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

Using the general term derived:

S37=372[250n4250]=372[250(37)4250]=372[92504250]=372[5000]=18500S_{37} = \frac{37}{2} [250n - 4250] = \frac{37}{2}[250(37) - 4250] = \frac{37}{2}[9250 - 4250] = \frac{37}{2}[5000] = 18500

Thus, the total profit at the end of January 2019 is €18500.

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