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3 years ago

The cost of 11 dvds and 7 cds is 172.50 and the cost of 10 dvds and 7 cds is 155.80. How much does a cd and dvd cost?

Mathematics

1 answer:

AleksandrR [38]3 years ago

5 0

Answer:

The question has a mistake

Step-by-step explanation:

11d+7c= 172.5

10d+7c= 155.8

By subtraction;

1d+ 0c = 16.7

1d = 16.7

11×16.7+7c=172.5

7c = 172.5-11*16.7

You will get a negative answer yet the cost cannot be negative.

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For the following amount at the given interest rate compounded continuously, find (a) the future value after 9 years, (b) the

Stella [2.4K]

Answer:

(a) The future value after 9 years is $7142.49.

(b) The effective rate is $r_E=4.759 \:{\%}$ .

(c) The time to reach $13,000 is 21.88 years.

Step-by-step explanation:

The definition of Continuous Compounding is

If a deposit of $P$ dollars is invested at a rate of interest $r$ compounded continuously for $t$ years, the compound amount is

$A=Pe^{rt}$

(a) From the information given

$P=4700$

$r=4.65\%=\frac{4.65}{100} =0.0465$

$t=9 \:years$

Applying the above formula we get that

$A=4700e^{0.0465\cdot 9}\\A=7142.49$

The future value after 9 years is $7142.49.

(b) The effective rate is given by

$r_E=e^r-1$

Therefore,

$r_E=e^{0.0465}-1=0.04759\\r_E=4.759 \:{\%}$

(c) To find the time to reach $13,000, we must solve the equation

$13000=4700e^{0.0465\cdot t}$

$4700e^{0.0465t}=13000\\\\\frac{4700e^{0.0465t}}{4700}=\frac{13000}{4700}\\\\e^{0.0465t}=\frac{130}{47}\\\\\ln \left(e^{0.0465t}\right)=\ln \left(\frac{130}{47}\right)\\\\0.0465t\ln \left(e\right)=\ln \left(\frac{130}{47}\right)\\\\0.0465t=\ln \left(\frac{130}{47}\right)\\\\t=\frac{\ln \left(\frac{130}{47}\right)}{0.0465}\approx21.88$

3 0

3 years ago

Need help on this as soon as possibke

miss Akunina [59]

LA = perimeter of base x height

Use Pythagorean theorem to find the base

4^2 + 6^2 = 52
Sq root of 52 is 7.2111...

4+6+7.2 = 17.2

17.2 x 8

137.6 is your answer

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3 years ago

If you borrowed $646 at an interest rate of 5% for 6 years, how much interest will you pay? Round to the nearest tenth if necess

Snezhnost [94]

Answer:

P=646

R=5%

T=2yrs

I=?

I=PRT/100

I= 646*5*2/100

I= 64.6

Step-by-step explanation:

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Answer:

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REY [17]

95.97

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