Answer:
it was 400 back then, a decade ago
Step-by-step explanation:
Answer:
40x = 1800 +25x
Step-by-step explanation:
To evaluate the probability that the lifespan will be between 1440 and 1465 hours will be given by:
P(1440<x<1465)
using the z-score formula we obtain:
z=(x-μ)/σ
where:
μ=1450
σ=8.5
hence
when x=1440
z=(1440-1450)/8.5
z=-1.18
P(z<-1.18)=0.1190
when x=1465
z=(1465-1450)/8.5
z=1.77
P(z<1.77)=0.9625
hence:
P(1440<x<1465)
=0.9625-0.1180
=0.8445
The answer is (-10) - 9= -19
