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3 years ago

Need help ASAP!!! Please comment if you know the answer I Really need help

Mathematics

2 answers:

zmey [24]3 years ago

5 0

I’m pretty sure it’s 65% please correct me if i’m wrong :)

liubo4ka [24]3 years ago

4 0

The answer is 65% because when you do 13/20 which will give you 0.65 which equals 65/100 which equals 65%.

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The ideal (daytime) noise-level for hospitals is 45 decibels with a standard deviation of 10 db; which is to say, this may not b

WINSTONCH [101]

Answer:

(a) A 99% confidence interval for the actual mean noise level in hospitals is (44.02 db, 49.98 db).

(b) We can be 90% confident that the actual mean noise level in hospitals is 47 db with a margin of error of 1.89 db.

(c) Unless our sample (of 81 hospitals) is among the most unusual 2% of samples, the actual mean noise level in hospitals is between 44.41 db and 49.59 db.

Step-by-step explanation:

The problem is incomplete. The questions are:

(a) A 99% confidence interval for the actual mean noise level in hospitals is (44.02 db, 49.98 db).

For a 99% CI, the value of z is z=2.58

Then, the confidence interval for the mean is:

$M-z\sigma/\sqrt{n}\leq\mu\leq M-z\sigma/\sqrt{n}\\\\47-2.58*10/\sqrt{75} \leq\mu\leq47+2.58*10/\sqrt{75}\\\\47-2.98\leq\mu\leq47+2.98\\\\44.02\leq\mu\leq 49.98$

(b) We can be 90% confident that the actual mean noise level in hospitals is 47 db with a margin of error of 1.89 db.

For a 90% CI, the value of z is z=1.64.

Then, we can calculate the margin of error as:

$E=z*\sigma/\sqrt{n}=1.64*10/\sqrt{75}=1.89$

(c) Unless our sample (of 81 hospitals) is among the most unusual 2% of samples, the actual mean noise level in hospitals is between 44.41 db and 49.59 db.

The 2% tails data corresponds, in the standard normal distirbution, to the values of z whose absolute value is higher than 2.33.

The values of db for these critical values are:

$X_1=M+z_1*\sigma/\sqrt{n}=47+(-2.33)*10/\sqrt{81}=47-2.59=44.41\\\\\\ X_2=M+z_2*\sigma/\sqrt{n}=47+(2.33)*10/\sqrt{81}=47+2.59=49.59$

3 0

4 years ago

Factor completely: 1. 9x^2 + 3x − 90

malfutka [58]

Answer:

9x^2+3x-90

81x+3x-90

84x-90 final answer

Step-by-step explanation:

7 0

3 years ago

Is f(x)=sqrt{x}+3x an exponential function?

nalin [4]

No, because in order to have an exponential function the value ‘e’ should be raised to a value of x. Since ‘e’ is not in this function, is is not an exponential function

8 0

3 years ago

a farmer has 10 acres to plant in wheat and rye. He has to plant at least 7 acres. However, he has only $1200 to spend and each

Jobisdone [24]

Answer:

4 acres of wheat and 4 acres of rye.

Step-by-step explanation:

Given: Farmer has only 7 acre, he has plant at least 7 acres.

Farmer has only $1200 to spend.

Each acre of wheat will cost $200 and rye will cost $100.

Planting time is only 12 hours

Wheat planting take 1 hour per hour and rye take 2 hours per acre.

Profit on wheat is $500 per acre and rye $300 per acre.

As to find out maximum profit, we need to plant maximum wheat.

While dividing number of acres of land for wheat and rye for plantation, we need to keep two constraint in the mind; Constraint of cost and time as given.

Lets assume few number considering these constraint to get maximum profit.

First assumption, 5 acres of wheat and 2 acres of rye

Time taken= $5\times 1= 5 h\\2\times 2= 2 h$

Total time taken 7 hours

Amount spent= $5\times 200= \$ 1000\\2\times 100= \$ 200$

Total cost is $ 1200.

Profit= $5\times 500= \$ 2500\\2\times 300= \$ 600$

Maximum profit= $3100.

Second assumption, 4 acres of wheat and 4 acres of rye.

Times taken= $4\times 1= 4 h\\4\times 2= 8 h$

Total time taken is 12 hours

Amount spent= $4\times 200= \$ 800\\4\times 100= \$ 400$

Total cost is $1200.

Profit= $4\times 500= \$ 2000\\4\times 300= \$ 1200$

Maximum profit= $3200.

∴ By using hit and trail method, we can see that we are getting maximum profit when farmer is planting 4 acres of wheat and 4 acres of rye.

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3 years ago

The work of a student to solve a set of equations is shown:

Ivahew [28]

Step 1. Equation B could not have simplified out to 3y= 3 - 4z because Equation A's original equation was y= 15 - 2z. That means after the multiplication by -3, -3(y)= -3(15 - 2z) it would equal -3y= -45 + 6z.

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4 years ago