Consider the following exponential probability density function.
f(x)=1/3e⁻ˣ/³ for x≥0
Which of the following is the formula for P(z≤2)?
1. P( ≤ 20) =e⁻ˣ₀/³
2. P(x≤ 20)=1-e⁻ˣ₀/³
3. P(≤10)=1-e⁻ˣ₀