Twenty low-intensity bulbs are tested for 120 hours each. One failed at 40 hours; all others completed the test. Calculate FR(%), FR(N) and MTBF.

Low-Intensity Bulbs

Light bulbs that emit a lower level of brightness compared to standard lighting options, often used to save energy.

FR(%)

An abbreviation possibly referring to Financial Ratio or Failure Rate, both of which quantify different business or operational metrics.

MTBF

Mean Time Between Failures, a measure used to predict the reliability and durability of a product or system.