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3 years ago

can i get some help? i tried figuring it out myself already but i must have done something wrong. please help!

Mathematics

1 answer:

zaharov [31]3 years ago

5 0

First, we'll set up two equations. One for the amount of each coin and another for the value of the coins.

N will represent nickels

D will represent dimes

N + D = 30

---The problem tells us that there are 30 total coins

0.05N + 0.10D = 2.95

---Nickels are worth 5 cents and dimes are worth 10 cents, and the total value of the coins is 2.95

Now that we have our equations, we need to solve for one of the variables in the first equation. I will solve for N.

N + D = 30

N = 30 - D

Then, we take that equation and substitute our new value for N into the second equation (value) and solve for D.

0.05(30 - D) + 0.10D = 2.95

1.5 - 0.05D + 0.10D = 2.95

1.5 + 0.05D = 2.95

0.05D = 1.45

D = 29

Now that we know how many dimes there are, we can plug that value into our equation for N and solve for N.

N = 30 - D

N = 30 - 29

N = 1

Therefore, there are 29 dimes and 1 nickel.

Hope this helps!

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$P(X \geq 6) = P(X=6) +P(X=7) +P(X=8) +P(X=9) +P(X=10)$

And using the probability mass function we got:

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And adding the values we got:

$P(X\geq 6) = 0.377$

The best answer would be:

D. 0.377

Step-by-step explanation:

Let X the random variable of interest, on this case we now that:

$X \sim Binom(n=10, p=0.5)$

The probability mass function for the Binomial distribution is given as:

$P(X)=(nCx)(p)^x (1-p)^{n-x}$

Where (nCx) means combinatory and it's given by this formula:

$nCx=\frac{n!}{(n-x)! x!}$

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And using the probability mass function we got:

$P(X=6)=(10C6)(0.5)^6 (1-0.5)^{10-6}=0.205$

$P(X=7)=(10C7)(0.5)^7 (1-0.5)^{10-7}=0.117$

$P(X=8)=(10C8)(0.5)^8 (1-0.5)^{10-8}=0.0439$

$P(X=9)=(10C9)(0.5)^9 (1-0.5)^{10-9}=0.0098$

$P(X=10)=(10C10)(0.5)^{10} (1-0.5)^{10-10}=0.000977$

And adding the values we got:

$P(X\geq 6) = 0.377$

The best answer would be:

D. 0.377

8 0

3 years ago