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>
Answer:
7 to the right
Step-by-step explanation:
Answer:
2/5
Step-by-step explanation:
-2/5-(-4/5) (remove the parentheses)
-2/5+4/5 (calculate)
solution: 2/5
hope this helps!
Answer:
All statements are correct for two congruent triangles
Step-by-step explanation:
If two triangles are congruent than the rules states that
Triangles are congruent when all corresponding sides and interior angles are congruent. The triangles will have the same shape and size, but one may be a mirror image of the other.
As the fig shows two triangle
Δ PQR
Δ LMN
All three corresponding sides of triangle are congruent
all three corresponding angles are congruent
Both triangle are of same size
Both are of same shape
hence all the statements are CORRECT
Keywords:Geometry
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