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:
n = -7,6
Step-by-step explanation:
n(n+1)+3=45
distributive property: a(b+c) = ab+ac
n²+n+3 = 45
n²+n -42 = 0
factor now
(n+7)(n-6) = 0
n = -7,6
A) .10 d + .25 q = 7.75
B) d + q = 40
Multiplying B) by -.10
B) -.10d -.10q = -4.0
Then adding this to A)
A) .10 d + .25 q = 7.75
.15q = 3.75
Quarters = 25
Therefore, dimes = 15
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Double-Check
A) .10 d + .25 q = 7.75
A) .10 * 15 d + .25 * 25 = 7.75
A) 1.50 + 6.25 = 7.75
Correct!!
Answer:
Kindly check explanation
Step-by-step explanation:
Given the question :
Jane evaluates x squared minus 3 x + 5 for x = negative 2 below. Step 1: (negative 2) squared minus 3 (negative 2) + 5 Step 2: Equals negative 4 + 6 + 5 Step 3: Equals 7 What, if any, was Jane's mistake?
Jane's evaluation :
x² - 3x + 5 for x = - 2
Step 1:
(-2)² - 3(-2) + 5
Step 2:
-4 + 6 + 5
Step 3 :
= 7
Jane's mistake was in STEP2,
evaluating (-2)² = 4 and not - 4
Hence, (-2)² - 3(-2) + 5
= 4 + 6 + 5
= 15
