A \( 21^{\circ} \mathrm{F} \) temperature rise (above its rating) can reduce the life of a ballast by - Select one: a. \( 50 \% \) b. \( 25 \% \) c. \( 75 \% \) d. \( 1 / 2 \% \)

The lifespan of electronic components, including ballasts, is significantly affected by temperature. A commonly used rule of thumb in electronics is that for every **10°C (approximately 18°F)** increase in operating temperature, the lifespan of the component **doubles in degradation**. In this case, a temperature rise of **21°F** is slightly above the 18°F benchmark, which aligns closely with the 10°C guideline. According to this rule: - **A 10°C (18°F) increase** in temperature typically **reduces the lifespan by about 50%**. Given that **21°F** is just above this threshold, the reduction in lifespan would still be approximately: **a. 50 %** **Answer:** **a. 50 %**