Understanding Percentages and Compound Measures
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Questions and Answers

What is the volume of a rectangular prism with dimensions 2 cm, 4 cm, and 5 cm?

  • 50 cm3
  • 20 cm3
  • 40 cm3 (correct)
  • 30 cm3
  • How would you compute the mass of an object if the density is 6 g/cm3 and the volume is 40 cm3?

  • M = 6 + 40
  • M = 6 - 40
  • M = 6 x 40 (correct)
  • M = 40 ÷ 6
  • If a force of 10 Newtons is applied to an area of 20 cm2, what pressure is produced?

  • 0.2 N/cm2
  • 2.0 N/cm2
  • 0.5 N/cm2 (correct)
  • 1.0 N/cm2
  • What is the result of converting 8 km/h into mph if 1 km = 1.6 miles?

    <p>12.8 mph (C)</p> Signup and view all the answers

    In the context of direct proportion, what does the equation y = kx represent?

    <p>y is in direct proportion to x with k as the multiplier (D)</p> Signup and view all the answers

    If the values d and t are directly proportional, what would the relationship be expressed as?

    <p>t = kd (A)</p> Signup and view all the answers

    Which of the following is NOT a unit for measuring pressure?

    <p>kg/m2 (A)</p> Signup and view all the answers

    What characterizes a graph showing direct proportion between two variables?

    <p>It is a straight line starting at (0,0). (A)</p> Signup and view all the answers

    What is the decimal equivalent of increasing an amount by 12%?

    <p>1.12 (A)</p> Signup and view all the answers

    How much does the plane travel in 15 minutes if it moves at a speed of 2000 km/hour?

    <p>250 km (B)</p> Signup and view all the answers

    What is the overall percentage increase when an amount is increased first by 10% and then by 12%?

    <p>23.2% (A)</p> Signup and view all the answers

    What is the density of a piece of metal with a mass of 40g and a volume of 4cm³?

    <p>10 g/cm³ (D)</p> Signup and view all the answers

    How do you calculate speed if given distance and time?

    <p>Speed = Distance ÷ Time (C)</p> Signup and view all the answers

    What is the total volume of a block of ice measuring 5cm by 2cm by 4cm?

    <p>30 cm³ (A)</p> Signup and view all the answers

    To convert 45 minutes into hours, how should it be expressed?

    <p>0.75 hours (C)</p> Signup and view all the answers

    If a plane travels for 1 hour at a speed of 600 km/h, how far does it travel?

    <p>600 km (D)</p> Signup and view all the answers

    What is the equation for y in terms of x, given that y is directly proportional to $x^2$ and when $x = 2$, $y = 16$?

    <p>y = 4x^2 (D)</p> Signup and view all the answers

    If g is proportional to the square root of f and when f = 9, g = 30, what is the equation for g in terms of f?

    <p>g = 10√f (B)</p> Signup and view all the answers

    What is the value of k when y is inversely proportional to x and given that when $x = 4$, $y = 25$?

    <p>100 (B)</p> Signup and view all the answers

    Given that y is inversely proportional to x, what is the solution for y when x is 2 and k is 100?

    <p>50 (C)</p> Signup and view all the answers

    How would you express g in terms of f if g is proportional to the square root of f with k = 10?

    <p>g = 10√f (B)</p> Signup and view all the answers

    If y is directly proportional to $x^2$, which of the following statements is true?

    <p>If x doubles, y quadruples. (B)</p> Signup and view all the answers

    What happens to y when x is increased by 50% in an inverse relationship?

    <p>y decreases by 50% (C)</p> Signup and view all the answers

    What does k represent in a proportional relationship?

    <p>The common multiplier (A)</p> Signup and view all the answers

    Flashcards

    Pressure

    A measure of the force applied per unit area.

    Direct Proportion

    Direct Proportion occurs when two quantities have a constant ratio. As one quantity increases, the other increases proportionally.

    y = kx

    The formula that connects two quantities in direct proportion. 'k' is the constant of proportionality.

    Constant of Proportionality (k)

    A multiplier that relates two directly proportional quantities. It stays constant regardless of the values of the quantities.

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    Percentage Multiplier

    A value used to represent a percentage increase. For example, a 10% increase is represented by a multiplier of 1.10, while a 12% increase is represented by a multiplier of 1.12.

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    Compound Measure

    A compound measure is a measurement that combines two or more different units. For example, speed combines distance and time, density combines mass and volume.

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    Speed

    Speed is a measure of how fast something is moving. It is calculated by dividing the distance travelled by the time taken. The formula is: Speed = Distance ÷ Time.

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    Density

    Density is a measure of how much mass is contained in a given volume. It is calculated by dividing the mass by the volume. The formula is: Density = Mass ÷ Volume.

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    Overall Percentage Increase

    To calculate the total percentage increase when multiple increases are applied, multiply the individual percentage multipliers together. For example, a 10% increase followed by a 12% increase results in an overall increase of 1.10 x 1.12 = 1.232 or 123.2%.

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    Compound Interest

    Compound interest is interest earned on both the original principal amount and on the accumulated interest from previous periods. This means that the interest grows exponentially over time.

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    Distance Calculation

    To find the distance traveled, multiply the speed of the object by the time it travels. This is also known as a distance, speed, and time problem.

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    Distance, Speed, Time Problems

    Distance, speed and time problems involve relationships between the distance traveled, the speed at which the object travels and the time taken to travel that distance.

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    Inverse Proportion

    A type of proportion where one quantity decreases as another increases.

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    Constant of Proportionality in Inverse Proportion (k)

    In the equation y = k/x, 'k' represents the constant of proportionality, which is the product of x and y in an inverse proportion relationship.

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    Direct Proportion with Powers

    A relationship where one quantity is directly proportional to the square of another quantity.

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    Study Notes

    Repeated Percentages

    • To increase an amount by 10%, multiply it by 1.10
    • To increase an amount by 12%, multiply it by 1.12
    • To find the overall percentage increase when increasing by multiple percentages, multiply the individual multipliers
    • For example, a 10% increase, then a 12% increase results in a 123.2% overall increase

    Compound Percentages

    • Compound interest calculates interest on the initial amount plus any accumulated interest.
    • Compound depreciation calculates depreciation on the initial amount plus any accumulated depreciation.
    • To calculate compound interest or depreciation, multiply the initial amount by the multiplier raised to the power of the number of years.
    • For example, if a £50,000 house increases by 10% each year for three years, it will be worth £66,550

    Compound Measures - Definitions

    • Density: The amount of mass in a volume. Indicates how tightly matter is packed. Measured in g/cm³, kg/m³ or kg/l.
    • Speed: The rate of change in distance over time. Measured in m/s, km/h, or mph.
    • Pressure: Force applied per unit area. Measured in N/m² or N/cm².
    • Fuel consumption: The distance a vehicle travels per unit of fuel volume. Measured in km/l or mpg.

    Compound Measures - Formulas

    • Speed: Speed = Distance ÷ Time, Time = Distance ÷ Speed, Distance = Speed x Time
    • Density: Density = Mass ÷ Volume, Volume = Mass ÷ Density, Mass = Density x Volume
    • Pressure: Force = Pressure x Area, Pressure = Force ÷ Area, Area = Force ÷ Pressure

    Compound Measures - Converting Measurements

    • Units of measurement can be converted using conversion factors. Various conversion examples are provided, such as converting km/h to mph or km/h to km/s, and mph to m/s

    Direct Proportion

    • Two sets of values have a direct proportion if they have a common multiplier.
    • The graph of a direct proportion is a straight line that passes through the origin.

    Direct Proportion - Formulas without powers

    • If y is directly proportional to x, then y = kx, where k is the constant of proportionality.
    • To find the formula for a directly proportional relationship between two variables, find the common multiplier by dividing corresponding pairs of values.
    • For example, if x = 6 and y = 18 and they are directly proportional then the equation is y = 3x

    Direct Proportion - Formulas with powers

    • If y is directly proportional to x³, then y = kx³.
    • If y is directly proportional to x², then y = kx².
    • Find the constant of proportionality by plugging corresponding values of x and y into the equation.

    Inverse Proportion

    • Two sets of values have an inverse proportion if one value increases and the other decreases.
    • If y is inversely proportional to x, then y = k/x, where k is the constant of proportionality.
    • To find the constant of proportionality for an inversely proportional relationship, multiply corresponding values of x and y. e.g y = 100/x if x = 4, y = 25 then 100 = 4 * 25.

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    Description

    This quiz covers key concepts related to repeated percentages, compound percentages, and definitions of compound measures such as density and speed. Test your knowledge on how to calculate overall percentage increases and understand the principles of compound interest and depreciation.

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