Let X denote the lifetime of light bulb. Given $X \sim Exp(\lambda)$ where the mean is $E(X) = 340 =\frac{1}{\lambda} \implies \lambda = \frac{1}{340} = 0.00294$ .

Recall that,

$\displaystyle P(X>x) = 1 - \int_0^x e^{-\lambda x} = 1 - (1 - e^{-\lambda x} = e^{-\lambda x}$

$\displaystyle P(X>220 | X>100) = \frac{P(X>220,X>100)}{P(X>100)} = \frac{e^{-\lambda \times 220}}{e^{-\lambda \times 100}} = \frac{0.5236}{0.7452} = 0.7026$

7 0

3 years ago

A student makes and sells designer T-shirts to earn extra cash. The material needed to make each T-shirt costs $4.25. Currently,

natita [175]

Step-by-step explanation:

Let x be the number of designer T shirts.

To break even,

Total Cost = Total Sales

Fixed Cost + Variable Cost = Total Sales

given the promotional advertising is classified under fixed cost,

$500 + 4.25x = 15x \\ 15x = 500 + 4.25x \\ 15x - 4.25x = 500 \\ 10.75x = 500 \\ x = 500 \div 10.75 \\ = 46.5 \\ = 47 \: (round \: off \: to \: nearest \: whole \: number)$

5 0

3 years ago

Divide round your answer to the nearest hundredth 5608.67÷7

Likurg_2 [28]

Answer:

5608.67 ÷ 7 = 801.24

4 0

4 years ago

Solve the inequality for y 2.9 < 5.6+y simplify your answer as much as possible

just olya [345]

Answer:

-2.7 < y

Step-by-step explanation:

2.9 < 5.6+y

Subtract 5.6 from each side

2.9-5.6 < 5.6-5.6+y

-2.7 < y

4 0

3 years ago