What is the sum of two odd numbers, two even numbers, and an odd number and an even number?

Correct Answer: A

Rationale: The sum of two odd numbers is even because odd numbers have a difference of 1 and adding them results in a multiple of 2. The sum of two even numbers is even because even numbers are multiples of 2. When an odd number and an even number are added, the result is odd because the even number contributes an extra 1 to the sum, making it an odd number. Therefore, the correct answer is A. Choices B, C, and D have incorrect combinations of the sum of odd and even numbers.

Correct Answer: A

Rationale: The correct formula for the area of a circle is A = πr², where π is a mathematical constant approximately equal to 3.14159 and r is the radius of the circle. Choice B, A = 2πr, represents the circumference of a circle, not the area. Choice C, A = πd, incorrectly uses the diameter (d) instead of the radius in the formula for area. Choice D, A = 2πd, is also related to the circumference of the circle, not the area. Therefore, option A is the only correct formula for calculating the area of a circle.

Correct Answer: A

Rationale: The correct way to find the radius of a circle when given the diameter is by dividing the diameter by 2 to get the radius (Radius = Diameter · 2). When given the circumference, you need to divide the circumference by 2π to find the radius (Radius = Circumference · 2π). Choice A provides the accurate formulas for finding the radius in both scenarios. Choices B, C, and D present incorrect formulas that do not align with the correct calculations for determining the radius of a circle based on the given information.

Correct Answer: A

Rationale: The correct formula to find the circumference of a circle is C = 2πr, where C represents the circumference and r is the radius of the circle. Choice B, Circumference = πr², represents the formula for the area of a circle rather than the circumference. Choice C, Circumference = 2r², is incorrect as it does not involve π in the formula. Choice D, Circumference = r²π, has the terms reversed compared to the correct formula; the formula should start with the constant (2) multiplied by π, followed by the radius.

Correct Answer: A

Rationale: The correct answer is A. The scatterplot depicts a clear linear association with a positive correlation between the two variables. Choice B is incorrect as the correlation is positive, not negative. Choice C is incorrect because the scatterplot does not show a nonlinear association. Choice D is incorrect as there is a distinguishable association present in the data.