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Paper II, Part I. Answer all questions in this part. 1. A rectangular garden is 18.6 m long and 12.4 m. A student measured the length as 18.2 m and the width as 12.7 m. Find the percentage error in the: i. Measured length ii. Calculated perimeter iii. Calculated area
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Step-by-step solution
39 stepsHere are the solutions to the problems:
1. To find the percentage error, we use the formula:
Given:
True length () = 18.6 m
True width () = 12.4 m
Measured length () = 18.2 m
Measured width () = 12.7 m
- i. Measured length
Calculate the absolute error in length.
$$ \text{Error in length} = |L_M - L_T| = |18.2 - 18.6| = |-0.4| = 0.4 \text{ m} $$Calculate the percentage error in length.
$$ \text{Percentage Error (Length)} = \frac{0.4}{18.6} \times 100\% \approx 2.1505\% $$ Rounded to two decimal places: $$ \boxed{\text{2.15%}} $$- ii. Calculated perimeter
Calculate the true perimeter and measured perimeter.
$$ P_T = 2(L_T + W_T) = 2(18.6 + 12.4) = 2(31.0) = 62.0 \text{ m} $$ $$ P_M = 2(L_M + W_M) = 2(18.2 + 12.7) = 2(30.9) = 61.8 \text{ m} $$Calculate the absolute error in perimeter.
$$ \text{Error in perimeter} = |P_M - P_T| = |61.8 - 62.0| = |-0.2| = 0.2 \text{ m} $$Calculate the percentage error in perimeter.
$$ \text{Percentage Error (Perimeter)} = \frac{0.2}{62.0} \times 100\% \approx 0.3226\% $$ Rounded to two decimal places: $$ \boxed{\text{0.32%}} $$- iii. Calculated area
Calculate the true area and measured area.
$$ A_T = L_T \times W_T = 18.6 \times 12.4 = 230.64 \text{ m}^2 $$ $$ A_M = L_M \times W_M = 18.2 \times 12.7 = 231.14 \text{ m}^2 $$Calculate the absolute error in area.
$$ \text{Error in area} = |A_M - A_T| = |231.14 - 230.64| = 0.50 \text{ m}^2 $$Calculate the percentage error in area.
$$ \text{Percentage Error (Area)} = \frac{0.50}{230.64} \times 100\% \approx 0.2168\% $$ Rounded to two decimal places: $$ \boxed{\text{0.22%}} $$2.
- a) Let be the initial number of boys and be the initial number of girls.
Set up equations based on the initial conditions.
From the first sentence, "In a class of 45 students, the number of boys is three times the number of girls." $$ B + G = 45 \quad (1) $$ $$ B = 3G \quad (2) $$Substitute equation (2) into equation (1) and solve for .
$$ 3G + G = 45 $$ $$ 4G = 45 $$ $$ G = \frac{45}{4} = 11.25 $$Substitute the value of back into equation (2) to find .
$$ B = 3 \times 11.25 = 33.75 $$ Note: The number of students must be whole numbers. This problem as stated leads to non-integer values, indicating a potential flaw in the question's numerical values. However, based on the direct interpretation of the initial conditions, these are the calculated values. Initial number of boys: $\boxed{\text{33.75}}$ Initial number of girls: $\boxed{\text{11.25}}$- b) Solve for in .
Express both sides of the equation with the same base.
$$ 7^{2x-1} = (7^2)^{x+2} $$ $$ 7^{2x-1} = 7^{2(x+2)} $$Equate the exponents.
$$ 2x-1 = 2(x+2) $$ $$ 2x-1 = 2x+4 $$Solve for .
$$ 2x - 2x = 4 + 1 $$ $$ 0 = 5 $$ This is a contradiction, which means there is no value of $x$ that satisfies the equation. The equation has $\boxed{\text{no solution}}$.3.
- a) The volume of a cylinder is 1386 cm. Its height is 14 cm. Find its radius. (Take )
Write down the formula for the volume of a cylinder.
$$ V = \pi r^2 h $$Substitute the given values into the formula.
$$ 1386 = \frac{22}{7} \times r^2 \times 14 $$Simplify and solve for .
$$ 1386 = 22 \times r^2 \times 2 $$ $$ 1386 = 44 r^2 $$ $$ r^2 = \frac{1386}{44} $$ $$ r^2 = 31.5 $$Solve for .
$$ r = \sqrt{31.5} $$ $$ r \approx 5.61248... \text{ cm} $$ Rounded to two decimal places: $$ r \approx \boxed{\text{5.61 cm}} $$- b) The 1st, 2nd and last terms of an Arithmetic Progression (A.P.) are 5, 11 and 59 respectively. Find the number of terms in the A.P.
Identify the first term (), second term (), and last term ().
$$ a_1 = 5 $$ $$ a_2 = 11 $$ $$ a_n = 59 $$Calculate the common difference ().
$$ d = a_2 - a_1 = 11 - 5 = 6 $$Use the formula for the -th term of an A.P., , to find .
$$ 59 = 5 + (n-1)6 $$Solve for .
$$ 59 - 5 = (n-1)6 $$ $$ 54 = 6(n-1) $$ $$ \frac{54}{6} = n-1 $$ $$ 9 = n-1 $$ $$ n = 9 + 1 $$ $$ n = \boxed{\text{10}} $$4. Table 2.1 shows the distribution of ages (in years) of 60 people in a community.
To calculate the mean age and standard deviation, we first find the midpoints () for each age group and then calculate and .Age (years) Midpoint () Frequency () 10 - 20 15 5 75 225 1125 20 - 30 25 12 300 625 7500 30 - 40 35 15 525 1225 18375 40 - 50 45 14 630 2025 28350 50 - 60 55 9 495 3025 27225 60 - 70 65 5 325 4225 21125 Total - i. Mean age
Use the formula for the mean of a grouped frequency distribution.
$$ \bar{x} = \frac{\sum f_i x_i}{\sum f_i} $$Substitute the calculated sums.
$$ \bar{x} = \frac{2350}{60} = \frac{235}{6} $$ $$ \bar{x} \approx 39.1666... \text{ years} $$ Rounded to two decimal places: $$ \bar{x} = \boxed{\text{39.17 years}} $$- ii. Standard deviation
Use the formula for the standard deviation of a grouped frequency distribution.
$$ \sigma = \sqrt{\frac{\sum f_i x_i^2}{\sum f_i} - \left(\frac{\sum f_i x_i}{\sum f_i}\right)^2} $$Substitute the calculated sums.
$$ \sigma = \sqrt{\frac{103700}{60} - \left(\frac{2350}{60}\right)^2} $$Calculate the values inside the square root.
$$ \sigma = \sqrt{1728.3333... - (39.1666...)^2} $$ $$ \sigma = \sqrt{1728.3333... - 1533.9166...} $$ $$ \sigma = \sqrt{194.4166...} $$Calculate the square root.
$$ \sigma \approx 13.9433... \text{ years} $$ Rounded to two decimal places: $$ \sigma = \boxed{\text{13.94 years}} $$5.
- a) Evaluate .
Integrate the polynomial term by term.
$$ \int (3x^2 - 2x + 5) dx = \frac{3x^{2+1}}{2+1} - \frac{2x^{1+1}}{1+1} + 5x + C $$ $$ = \frac{3x^3}{3} - \frac{2x^2}{2} + 5x + C $$ $$ = x^3 - x^2 + 5x + C $$Evaluate the definite integral using the limits of integration.
$$ [x^3 - x^2 + 5x]_{0}^{2} = (2^3 - 2^2 + 5(2)) - (0^3 - 0^2 + 5(0)) $$ $$ = (8 - 4 + 10) - (0) $$ $$ = 14 - 0 $$ $$ = \boxed{\text{14}} $$- b) Solve for if .
Use the logarithm property to combine the terms on the left side.
$$ \log((x+2)(2x-1)) = \log 15 $$Equate the arguments of the logarithms.
$$ (x+2)(2x-1) = 15 $$Expand the left side and rearrange into a quadratic equation.
$$ 2x^2 - x + 4x - 2 = 15 $$ $$ 2x^2 + 3x - 2 = 15 $$ $$ 2x^2 + 3x - 17 = 0 $$Use the quadratic formula to solve for .
$$ x = \frac{-3 \pm \sqrt{3^2 - 4(2)(-17)}}{2(2)} $$ $$ x = \frac{-3 \pm \sqrt{9 + 136}}{4} $$ $$ x = \frac{-3 \pm \sqrt{145}}{4} $$Check for valid solutions.
The arguments of the logarithms must be positive, so and . Thus, must be greater than 0.5. This solution is valid since . This solution is not valid since .
Therefore, the only valid solution is:Handwritten Questions:
Square both sides of the equation.
$$ (\sqrt{2x+6})^2 = 10^2 $$ $$ 2x+6 = 100 $$Solve for .
$$ 2x = 100 - 6 $$ $$ 2x = 94 $$ $$ x = \frac{94}{2} $$ $$ x = \boxed{\text{47}} $$Square both sides of the equation.
$$ (\sqrt{3x+1})^2 = 4^2 $$ $$ 3x+1 = 16 $$Solve for .
$$ 3x = 16 - 1 $$ $$ 3x = 15 $$ $$ x = \frac{15}{3} $$ $$ x = \boxed{\text{5}} $$
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