Mathematics for IGCSE & O level - Probability (Section 6 - No. 3)
A weather forecast states a 20% chance of rain. What are the odds against rain (in fractional form)?
1/5
4/5
1/4
4/1
解释
If the chance of rain is 20%, the chance of no rain is 80%. This gives odds of 80:20 or 4:1 (against rain). Expressed as a fraction, this is 4/1.