1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
Assoli18 [71]
3 years ago
6

if the area of a circle is represented by A=21π, what is the radius of the circle? round your answer to the nearest tenth

Mathematics
1 answer:
Reptile [31]3 years ago
5 0
The equation is actually
circle area = PI * radius^2
radius = square root (area / PI)


You might be interested in
. Mrs. Rojas deposited $8000 into an account paying 4% interest annually. After 8 months Mrs. Rojas withdrew the $6000 plus inte
Mashcka [7]

well, keeping in mind that a year has 12 months, that means that 8 months is 8/12 of a year, when Mrs Rojas pull her money out.

~~~~~~ \textit{Simple Interest Earned Amount} \\\\ A=P(1+rt)\qquad \begin{cases} A=\textit{accumulated amount}\\ P=\textit{original amount deposited}\dotfill & \$6000\\ r=rate\to 4\%\to \frac{4}{100}\dotfill &0.04\\ t=years\to \frac{8}{12}\dotfill &\frac{2}{3} \end{cases} \\\\\\ A=6000[1+(0.04)(\frac{2}{3})]\implies A=6000\left( \frac{77}{75} \right)\implies A=6160

well, she put in 6000 bucks, got back 160 extra, that's the interest earned in the 8 months.

what if she had left her money for 1 whole year, then

~~~~~~ \textit{Simple Interest Earned Amount} \\\\ A=P(1+rt)\qquad \begin{cases} A=\textit{accumulated amount}\\ P=\textit{original amount deposited}\dotfill & \$6000\\ r=rate\to 4\%\to \frac{4}{100}\dotfill &0.04\\ t=years\dotfill &1 \end{cases} \\\\\\ A=6000[1+(0.04)(1)]\implies A=6240

so had she left it in for a year, she'd have gotten 6240, namely 240 in interest, well, what fraction of a year's interest was earned? or worded differently, what fraction is 160(8 months) of 240(1 year)?

\cfrac{\stackrel{\textit{for 8 months}}{160}}{\underset{\textit{for 12 months}}{240}}\implies \cfrac{2}{3}

4 0
2 years ago
Round 3,942,588 to the nearest thousand.
olchik [2.2K]
Hey there! :D

3,942,588

The thousandths is where the 2 is. 

If the number behind the 2 is 5 or greater, we round up to 3.

It is, so round up:

3,943,000 <== rounded number

I hope this helps!
~kaikers

5 0
3 years ago
Read 2 more answers
Memory module consists of 9 chips. The device is designed with redundancy so that it works even if one of its chips is defective
soldier1979 [14.2K]

Answer:

a) P[C]=p^n

b) P[M]=p^{8n}(9-8p^n)

c) n=62

d) n=138

Step-by-step explanation:

Note: "Each chip contains n transistors"

a) A chip needs all n transistor working to function correctly. If p is the probability that a transistor is working ok, then:

P[C]=p^n

b) The memory module works with when even one of the chips is defective. It means it works either if 8 chips or 9 chips are ok. The probability of the chips failing is independent of each other.

We can calculate this as a binomial distribution problem, with n=9 and k≥8:

P[M]=P[C_9]+P[C_8]\\\\P[M]=\binom{9}{9}P[C]^9(1-P[C])^0+\binom{9}{8}P[C]^8(1-P[C])^1\\\\P[M]=P[C]^9+9P[C]^8(1-P[C])\\\\P[M]=p^{9n}+9p^{8n}(1-p^n)\\\\P[M]=p^{8n}(p^{n}+9(1-p^n))\\\\P[M]=p^{8n}(9-8p^n)

c)

P[M]=(0.999)^{8n}(9-8(0.999)^n)=0.9

This equation was solved graphically and the result is that the maximum number of chips to have a reliability of the memory module equal or bigger than 0.9 is 62 transistors per chip. See picture attached.

d) If the memoty module tolerates 2 defective chips:

P[M]=P[C_9]+P[C_8]+P[C_7]\\\\P[M]=\binom{9}{9}P[C]^9(1-P[C])^0+\binom{9}{8}P[C]^8(1-P[C])^1+\binom{9}{7}P[C]^7(1-P[C])^2\\\\P[M]=P[C]^9+9P[C]^8(1-P[C])+36P[C]^7(1-P[C])^2\\\\P[M]=p^{9n}+9p^{8n}(1-p^n)+36p^{7n}(1-p^n)^2

We again calculate numerically and graphically and determine that the maximum number of transistor per chip in this conditions is n=138. See graph attached.

6 0
3 years ago
A water tank that holds 30 gallons of water when full is leaking 3/4 gallon of water every hour. If no one notices and stops the
viva [34]
It will take 40 hours for the water tank to become empty.

Explanation:
Divide 30 by 0.75 (equivalent to 3/4). 
7 0
2 years ago
Javier earned the following scores on his first five tests: 77, 89, 84, 80, and 85. What score did he earn on his last test to h
Colt1911 [192]
You would have eto get an 89
3 0
3 years ago
Other questions:
  • Find the area of the shaded portion in the square.
    15·2 answers
  • The sampling distribution of certain statistical measures shows a normal distribution which of the following is an unbiased esti
    14·2 answers
  • In which group would one friend get the most money ?
    8·1 answer
  • Express 8.21 as a mixed number
    5·1 answer
  • What is the length of a rectangle with a width of 10 cm and area of 120 cm???
    14·1 answer
  • Sam decides to build a square garden. If the area of the garden is 9x2 − 24x + 16 square feet, what is the length of one side of
    9·2 answers
  • 10
    13·2 answers
  • Whose correct &amp; whats an equation to solve for x.
    13·1 answer
  • ITS AN EDUCATIONAL EMERGENCY!!! This is due tonight how do I solve this?? PLEASE HELPP
    12·1 answer
  • EB bisects ∠RED. Find the measure of ∠BED if ∠REB = 5x – 3 and ∠RED = 8x + 16<br><br>plzzzzzzzzzzz
    14·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!