Answer: sqrt(byx × bxy).
- A byx × bxy
- B sqrt(byx × bxy)
- C (byx + bxy)/2
- D byx/bxy
Correct answer: B. sqrt(byx × bxy)
Explanation: By definition byx = r·(σy/σx) and bxy = r·(σx/σy). Their product: byx × bxy = r²·(σy/σx)·(σx/σy) = r². Therefore r = ±√(byx × bxy), with sign matching that of both coefficients.
In a perfectly normal (bell-shaped) distribution, mean, median, and mode all coincide at the centre; about 68% of data falls within 1 standard deviation of the mean, 95% within 2, and 99.7% within 3 - the empirical rule used to judge how typical or extreme a value is.
Concept context
Mean, median, mode, standard deviation, and data interpretation