Answer:
1. 90% 2. 10% 3. 50%
Step-by-step explanation:
Standard Deviation (σ) = 50 days
Average/Mean (μ) = 300days
Probability that it would last more than 300 days = P(Bulb>300 days)
We will assume there are 365 days in a year.
P(Bulb>300 days) implies that the bulb would
Using the normal equation;
z = standard/normal score = (x-μ)/σ where x is the value to be standardized
P(Bulb>300 days) implies x = 365 days
Therefore z = (365-300)/50 = 1.3
Using the normal graph for z=1.3, probability = 90%
2. P(Bulb<300 days) = 1 - P(Bulb>300 days)\
P(Bulb<300 days) = 1 - 0.9
P(Bulb<300 days) = 10%
3. P(Bulb=300 days) implies z=0 since x=300
Using the normal graph for z=0, probability =50%
