The complimentary event is the probability of it not raining. The probability of that is 1-2/5 = 3/5.
Given that mean=3750 hours and standard deviation is 300:
Then:
<span>a. The probability that a lamp will last for more than 4,000 hours?
P(x>4000)=1-P(x<4000)
but
P(x<4000)=P(z<Z)
where:
z=(x-</span>μ)/σ
z=(4000-3750)/300
z=0.833333
thus
P(x<4000)=P(z<0.8333)=0.7967
thus
P(x>4000)=1-0.7967=0.2033
<span>b.What is the probability that a lamp will last less than 3,000 hours?
P(x<3000)=P(z<Z)
Z=(3000-3750)/300
z=-2.5
thus
P(x<3000)=P(z<-2.5)=0.0062
c. </span><span>.What lifetime should the manufacturer advertise for these lamps in order that only 4% of the lamps will burn out before the advertised lifetime?
the life time will be found as follows:
let the value be x
the value of z corresponding to 0.04 is z=-2.65
thus
using the formula for z-score:
-2.65=(x-3750)/300
solving for x we get:
-750=x-3750
x=-750+3750
x=3000</span>
U turn negative numbers from mixed numbers to improper fractions the same way u do with positive...u just temporarily disregard the negative sign.
Example :
- 2 2/3.....temporarily disregard the negative sign......take ur whole number (2) and multiply it by ur denominator (3) giving u 6, then add that to ur numerator (2) giving u 8....then put that number over the original denominator (3) giving u 8/3...and then put back ur negative sign...-8/3
Answer:
$75
Step-by-step explanation:
First, we will find how many hours he worked. 8:00-12:00 is 4 hours, and 12:00-2:00 is 2 hours, so he worked a total of 6 hours.
Next, we have to multiply the hours worked by his hourly wage.
12.50*6=75
