Which equation correctly computes the overall average for two groups with known averages and sizes? Group A: 90 (8), Group B: 85 (6).

Unlock all questions

This demo includes only 20 questions. Upgrade to access hundreds of questions, flashcards, exam simulations, and disable ads.

Full question bankExam simulationsFlashcards
From $24.99Unlock all

Prepare for the BWS Academics Shell Test. Engage with flashcards and multiple choice questions, complemented by hints and explanations. Ace your exam with confidence!

Multiple Choice

Which equation correctly computes the overall average for two groups with known averages and sizes? Group A: 90 (8), Group B: 85 (6).

Explanation:
When combining group means with different sizes, you use a weighted average: multiply each group’s mean by its size, add those products, and then divide by the total number of observations. Here, Group A has an average of 90 across 8 items, and Group B has 85 across 6 items. So the overall average is (90×8 + 85×6) ÷ (8+6) = (720 + 510) ÷ 14 = 1230/14 ≈ 87.86. This matches the expression that weights each mean by its group size and divides by the total size. Using the wrong weights, ignoring sizes, or dividing by an incorrect total would yield a different value.

When combining group means with different sizes, you use a weighted average: multiply each group’s mean by its size, add those products, and then divide by the total number of observations. Here, Group A has an average of 90 across 8 items, and Group B has 85 across 6 items. So the overall average is (90×8 + 85×6) ÷ (8+6) = (720 + 510) ÷ 14 = 1230/14 ≈ 87.86. This matches the expression that weights each mean by its group size and divides by the total size. Using the wrong weights, ignoring sizes, or dividing by an incorrect total would yield a different value.

More Multiple Choice Questions
Subscribe

Get the latest from Passetra

You can unsubscribe at any time. Read our privacy policy