Answer:
A= 3r^2
Step-by-step explanation:
Answer:
Step-by-step explanation: Let x = number of $5 bills
Let y = number of $10 bills
Use these variables to set up equations to represent total deposit and number of bills.
x + y = 38 eq1 ----> total number of bills
5x + 10y = 220 eq2 -----> total deposit
Answer:
Step-by-step explanation:
$15,000×0.08 = $1,200 interest for 360 days
$1,200 × 30/360 = $100 interest
Answer:
<u>The company should promote a lifetime of </u><u>3589 hours</u><u> for these bulbs, so that only 2% of them burnout before the claimed lifetime.</u>
Step-by-step explanation:
Consider the lifetime of light bulbs is normally distributed. Then, μ = 4000 hours and σ = 200 hours.
Let X be the lifetime of bulbs. We need to find the lifetime before which only 2% (0.02) of the bulbs burn out. Suppose the value of this lifetime is y. then, we need to find out P(X<y) = 0.02.
We will use the z-score formula:
<u>z = (x-μ)/σ</u>
P(X<y) = 0.02
P((X-μ)/σ < (y-μ)/σ) = 0.02
P(z < (y-4000)/200) = 0.02
We can find the value of z at which the probability is 0.02 from the normal distribution (areas under the normal curve) table.
From the table we can see that 0.02 lies between z values -2.05 and -2.06. So,
z = [-2.05 + (-2.06)]/2
= -4.11/2
z = -2.055
So,
(y-4000)/200 = -2.055
y-4000 = -411
y = 4000 - 411
y = 3589 hours
<u></u>
<u>The company should promote a lifetime of </u><u>3589 hours</u><u> for these bulbs, so that only 2% of them burnout before the claimed lifetime.</u>
