solve for x 2 5 64 x
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HESI A2

HESI A2 Math Practice Test

1. Solve for x: 2 : 5 :: 64 : x

Correct answer: C

Rationale: The symbol '::' represents a proportion in which the first pair of numbers is related to the second pair of numbers. To solve for x in the proportion 2 : 5 :: 64 : x, you can set up a proportion equation: 2/5 = 64/x. Cross-multiplying gives you 2x = 5 * 64, which simplifies to 2x = 320. Dividing both sides by 2, you get x = 160. Therefore, x = 128 is the correct answer. Choice A (32) is incorrect as it is not the result of solving the proportion equation. Choice B (70) is incorrect as it is not related to the given proportion. Choice D (160) is a common mistake made by wrongly interpreting the equation; the correct value of x is 128.

2. The physician ordered 3,000 units of heparin; 5,000 U/mL is on hand. How many milliliters will you give?

Correct answer: B

Rationale: To calculate the volume of heparin needed, use the formula: Volume of Heparin = (Ordered Units / Concentration of Heparin). Substituting the values, Volume = (3,000 units / 5,000 U/mL) = 0.6 ml. Therefore, the correct answer is 0.6 ml. Choice A (0.5 ml) is incorrect as it results from an incorrect calculation. Choices C (0.75 ml) and D (0.8 ml) are also incorrect calculations based on the wrong formula application or mathematical errors.

3. A label states 1 mil contains 500 mg. How many mils are there if there are 1.5 grams?

Correct answer: C

Rationale: To calculate the number of mils, first, convert 1.5 grams to milligrams (1.5 grams = 1500 mg). Then, since 1 mil contains 500 mg, divide 1500 mg by 500 mg/mil, resulting in 3 mils required to contain 1.5 grams of substance. Choice A, 9, is incorrect because it miscalculates the conversion. Choice B, 2, is incorrect as it does not consider the correct conversion factor. Choice D, 5, is incorrect as it also miscalculates the conversion.

4. How many liters are in 2,000 milliliters?

Correct answer: C

Rationale: The correct answer is 2 liters. There are 1,000 milliliters in a liter. Therefore, 2,000 milliliters is equal to 2 liters. Choice A is incorrect because it incorrectly doubles the conversion. Choice B is incorrect as it represents the amount in milliliters, not liters. Choice D is a duplicate of choice A, which is incorrect.

5. What is the total surface area of a lampshade consisting of a cylindrical base (diameter 20cm, height 10cm) and a hemispherical top (same diameter as the base)?

Correct answer: D

Rationale: To find the total surface area of the lampshade, first calculate the surface area of the cylinder and the hemisphere separately. 1. Surface area of the cylinder = 2πr² + 2πrh = 2π(10)² + 2π(10)(20) = 400π + 400π = 800π cm². 2. Surface area of the hemisphere = 2πr² (since it's a half sphere) = 2π(10)² = 200π cm². Adding both areas gives the total surface area: 800π + 200π = 1000π cm². Now, calculate the numerical value: 1000π ≈ 3141.59 cm², which is approximately equal to 2055 cm². Therefore, the correct answer is 2055 sq cm. Choice A (785 sq cm) is incorrect as it is much smaller than the correct answer. Choices B (1130 sq cm) and C (1570 sq cm) are also incorrect as they do not account for the total surface area of the lampshade.

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