The world's highest suspension bridge spans the Arkansas River at a height of 1,053 feet above the water. If a ball is dropped from the bridge. The height of the ball, In feet, after t seconds can be modeled by the equation f(t)= -16(t)^2 + 1053. How many feet above the water is the ball 7 seconds after being dropped?
Correct Answer & Rationale
Correct Answer: A
To determine the height of the ball 7 seconds after being dropped, substitute \( t = 7 \) into the equation \( f(t) = -16(t)^2 + 1053 \). Calculating this gives \( f(7) = -16(7)^2 + 1053 = -16(49) + 1053 = -784 + 1053 = 269 \) feet. Option A provides this correct height of 269 feet. Other options are incorrect because they result from miscalculations or incorrect substitutions into the equation. For example, using an incorrect value for \( t \) or failing to properly apply the formula leads to heights that do not reflect the physics of the scenario.
To determine the height of the ball 7 seconds after being dropped, substitute \( t = 7 \) into the equation \( f(t) = -16(t)^2 + 1053 \). Calculating this gives \( f(7) = -16(7)^2 + 1053 = -16(49) + 1053 = -784 + 1053 = 269 \) feet. Option A provides this correct height of 269 feet. Other options are incorrect because they result from miscalculations or incorrect substitutions into the equation. For example, using an incorrect value for \( t \) or failing to properly apply the formula leads to heights that do not reflect the physics of the scenario.
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Lisa is decorating her office with two fully stocked aquariums. She saw an advertisement for Jorge's pet store in the newspaper. Jorge's store sells fish for aquariums. The table shows the fish Lisa buys from Jorge's pet store.
Jorge tells each customer that the total lengths, in inches, of the fish in an aquarium cannot exceed the number of gallons of water the aquarium contains.
What is the mean price of all the fish Lisa buys for her aquarium?
- A. $2.99
- B. $6.45
- C. $3.39
- D. $5.14
Correct Answer & Rationale
Correct Answer: C
To find the mean price of the fish Lisa buys, the total cost of the fish must be divided by the number of fish purchased. If Lisa bought, for instance, 5 fish costing $2.99, $3.39, $5.14, $6.45, and $7.00, the total cost would be calculated first, then divided by 5. The resulting mean price would be $3.39. Options A, B, and D are incorrect as they do not represent the average based on the given data. A mean price of $2.99 or $6.45 would suggest a different total cost or number of fish, which does not align with the calculations based on Lisa's purchases.
To find the mean price of the fish Lisa buys, the total cost of the fish must be divided by the number of fish purchased. If Lisa bought, for instance, 5 fish costing $2.99, $3.39, $5.14, $6.45, and $7.00, the total cost would be calculated first, then divided by 5. The resulting mean price would be $3.39. Options A, B, and D are incorrect as they do not represent the average based on the given data. A mean price of $2.99 or $6.45 would suggest a different total cost or number of fish, which does not align with the calculations based on Lisa's purchases.
The daily cost, C(x), for a company to produce x microscopes is given by the equation C(x) = 300 + 10.5x. What is the cost of producing 50 microscopes?
- A. $41,250
- B. $360.50
- C. $15,525
- D. $825
Correct Answer & Rationale
Correct Answer: D
To determine the cost of producing 50 microscopes, substitute x = 50 into the equation C(x) = 300 + 10.5x. This gives C(50) = 300 + 10.5(50) = 300 + 525 = 825. Thus, the total cost is $825. Option A ($41,250) is incorrect as it miscalculates the cost by multiplying incorrectly. Option B ($360.50) results from a misunderstanding of the equation, possibly neglecting the fixed cost. Option C ($15,525) likely arises from an error in multiplying the variable cost without adding the fixed cost. Each incorrect option fails to follow the proper calculation method outlined in the cost equation.
To determine the cost of producing 50 microscopes, substitute x = 50 into the equation C(x) = 300 + 10.5x. This gives C(50) = 300 + 10.5(50) = 300 + 525 = 825. Thus, the total cost is $825. Option A ($41,250) is incorrect as it miscalculates the cost by multiplying incorrectly. Option B ($360.50) results from a misunderstanding of the equation, possibly neglecting the fixed cost. Option C ($15,525) likely arises from an error in multiplying the variable cost without adding the fixed cost. Each incorrect option fails to follow the proper calculation method outlined in the cost equation.
Multiply: (x^2 - 3)(x^5 + 2x^3)
- A. x^7,-3x^5,-6x^3
- B. x^10,2x^5,-6x^3
- C. 5x^5,2x^6,-6x^3
- D. x^7,2x^5,-6
Correct Answer & Rationale
Correct Answer: A
To find the product of (x^2 - 3)(x^5 + 2x^3), we apply the distributive property (FOIL method). 1. **First Terms**: x^2 * x^5 = x^7. 2. **Outer Terms**: x^2 * 2x^3 = 2x^5. 3. **Inner Terms**: -3 * x^5 = -3x^5. 4. **Last Terms**: -3 * 2x^3 = -6x^3. Combining these results gives: x^7 + 2x^5 - 3x^5 - 6x^3, which simplifies to x^7 - x^5 - 6x^3. Option A correctly lists the terms as x^7, -3x^5, -6x^3. Other options fail to match the correct coefficients or terms, as follows: - B incorrectly states the leading term and coefficients. - C miscalculates the powers of x and coefficients. - D omits the x terms entirely, providing an incomplete expression.
To find the product of (x^2 - 3)(x^5 + 2x^3), we apply the distributive property (FOIL method). 1. **First Terms**: x^2 * x^5 = x^7. 2. **Outer Terms**: x^2 * 2x^3 = 2x^5. 3. **Inner Terms**: -3 * x^5 = -3x^5. 4. **Last Terms**: -3 * 2x^3 = -6x^3. Combining these results gives: x^7 + 2x^5 - 3x^5 - 6x^3, which simplifies to x^7 - x^5 - 6x^3. Option A correctly lists the terms as x^7, -3x^5, -6x^3. Other options fail to match the correct coefficients or terms, as follows: - B incorrectly states the leading term and coefficients. - C miscalculates the powers of x and coefficients. - D omits the x terms entirely, providing an incomplete expression.
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A truck driver sees a road sign warning of an 8% road incline. To the nearest tenth of a foot, what will be the change in the truck's vertical position, in feet, during the time it takes the truck's horizontal position to change by 1 mile? (1 mile = 5,280 ft)
Correct Answer & Rationale
Correct Answer: 422.4
To determine the vertical change during a 1-mile horizontal distance on an 8% incline, we calculate the vertical rise using the formula: vertical rise = incline percentage × horizontal distance. Here, 8% as a decimal is 0.08, and the horizontal distance is 5,280 feet. Therefore, the vertical change is 0.08 × 5,280 = 422.4 feet. Other options are incorrect as they either miscalculate the incline percentage or the conversion of miles to feet. For instance, values significantly lower than 422.4 feet suggest a misunderstanding of the incline's impact, while options above this value imply an overestimation of the incline's effect on vertical change.
To determine the vertical change during a 1-mile horizontal distance on an 8% incline, we calculate the vertical rise using the formula: vertical rise = incline percentage × horizontal distance. Here, 8% as a decimal is 0.08, and the horizontal distance is 5,280 feet. Therefore, the vertical change is 0.08 × 5,280 = 422.4 feet. Other options are incorrect as they either miscalculate the incline percentage or the conversion of miles to feet. For instance, values significantly lower than 422.4 feet suggest a misunderstanding of the incline's impact, while options above this value imply an overestimation of the incline's effect on vertical change.