In an AB test, version X has a conversion rate of 3% and version Y has 4%. By what percentage does Y exceed X?

• A. 3.33%
• B. 33.33%
• C. 33.3%
• D. 34%

Answer: (B)

When measuring how much one rate is higher than another, use the relative increase: how big the change is compared to the original rate. Y goes from 3% to 4%, so the change is 1 percentage point. To see how large that is relative to X, divide that change by X: 1% ÷ 3% = 1/3 ≈ 0.3333. Convert to a percentage: 33.333...%. Rounding to two decimals gives 33.33%, which is why that option is correct. The 3.33% and 34% options don’t reflect that relative increase, and 33.3% is a rounding choice with one fewer decimal.