I know I've been asking a lot but I really don't understand. It's due for tomorrow so please help as much as possible thanks xx

A certain brand of flood lamps has a lifetime that is normally distributed with a mean of 3,750 hours and a standard deviation o

vesna_86 [32]

Given that mean=3750 hours and standard deviation is 300:
Then:
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-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

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. .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

7 0

3 years ago

Please help ASAP!!!!

Inga [223]

A negative times a negative is a positive, and a negative times a positive is equal to a negative. I’ve never used that program so if that what u need help with sorryyy

5 0

3 years ago

the sum of three consecutive integers is 186. what are the integers? the first integer is _ the second integer is _ the third in

UNO [17]

The integers are x - 1, x and x + 1

x - 1 + x + x + 1 = 186
3x = 186
x = 186/3 = 62

Therefore, the numbers are 61, 62 and 63

7 0

3 years ago

Read 2 more answers

A campus club held a bake sale as a fund raiser, selling coffee, muffins, and bacon and eggs sandwiches. The club members charge

OLEGan [10]

Answer:

The number of bacon and egg sandwiches sells are 2 .

Step-by-step explanation:

Let us assume that the number of coffee cups campus club sells be x .

Let us assume that the number of muffins cups campus club sells be y .

Let us assume that the number of bacon and eggs sandwiches campus club sells be z .

As given

Campus club sold a total of 55 items .

Thus the equation becomes

x + y + z = 55

Of the club members sold 5 more muffins than cups of coffee .

Thus

Number of muffins = 5 + Number of cups of coffee

y = 5 + x

Putting the value of y in the equation x + y + z = 55 .

x + 5 + x + z = 55

2x + z = 55- 5

2x + z = 50

As given

The club members charged $1 for a cup of coffee, 3$ for a muffin , and $4 for a bacon and egg sandwich and earns $119 .

Thus the equation becomes

x + 3y + 4z = 119

Putting the value of y in the above

x + 3 × (x + 5) + 4z = 119

x + 3x + 15 + 4z = 119

4x + 4z = 119 - 15

4x + 4z = 104

Simplify the above

x + z = 26

Thus the two equations are

2x + z = 50

x + z = 26

Multiply x + z = 26 subtracted from 2x + z = 50.

2x -x + z - z = 50 - 26

x = 24

Put the value of x in x + z = 26 .

24 + z =26

z = 26 - 24

z = 2

Therefore the number of bacon and egg sandwiches sells are 2 .

7 0

3 years ago

X-4= x−4= \,\,-4+x −4+x

earnstyle [38]

I believe the answer should be -4+x= -4x.
I hope this helps :)

7 0

1 year ago