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2 years ago

You went shopping for back to school and bought packs of pens and pencils. a pack of

Mathematics

1 answer:

Scrat [10]2 years ago

7 0

Answer:

5 packs of pens and 8 packs of pencils.

Step-by-step explanation:

Let the Pn and Pl stand for the number of packs of pens (Pn) and pencils (Pl) purchased.

We know that each pack of pens is $3 and each pack of pencils is $2.50.

We are also told that Pn + Pl = 13 [In total, 13 packs were purchased].

And we're told that $35 was spent.

The $35 must equal: $3*Pn + $2.5*Pl [the sum of the number of packs of each times the price per pack for each]

3*Pn + 2.5*Pl = 35

Rearrange the first equation:

Pn + Pl = 13

Pn = 13 - Pl

Use this definition of Pn in the second equation:

3*Pn + 2.5*Pl = 35

3*(13 - Pl) + 2.5*Pl = 35

39 - 3Pl + 2.5Pl = 35

-0.5Pl = -4

Pl = 8

8 packs of pencils (Pl) were purchased.

This means the packs of pens purchased must be 5, since a total of 13 packs were purchased.

Check:

Does 5 packs of pens and 8 packs of pencils total $35?

5*($3) + 8*($2.5) = $35 ??

$15 + $20 = $35 ?

YES

You bought 5 packs of pens and 8 packs of pencils.

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A furniture store is having a sale on sofas and you're going to buy one. The advertisers know that buyers get to the store and t

MrRissso [65]

Answer:

$290

Step-by-step explanation:

We are told that 1 out of 5 buyers change to a more expensive sofa than the one in the sale advertisement.

Now we are told that the advertised sofa is $250 and the more expensive sofa is $450.

Thus;

P(x) for expensive sofa = 1/5

P(x) for sofa in sale advertisement = 4/5

Thus, expected value is;

E(X) = (1/5)450 + (4/5)250

E(x) = 90 + 200

E(x) = $290

6 0

3 years ago

Combine like terms . Please help me I am an vacation and I don't know how to do this

Georgia [21]

2x^4
13b-10
5y+10
5a^3
2b^2+8a

8 0

3 years ago

Suppose Jessica opens a savings account with $5000 that compounds interest daily. The APR at the time Jessica opens the account

IrinaK [193]

Hi there

1+0.035=(1+r/360)^360
Solve for r
R=(((1.035)^(1÷360)−1)×360)×100
R=3.44%

6 0

3 years ago

It is a well-known fact that 50% of the general population are rascals (P(R) = 0.5) and 50% of the general population are not ra

aleksley [76]

Answer:

The answer is D. 0.75

Step-by-step explanation:

Let call R the event that a person is rascal, RC a person is not rascal, TH a person use top hat and NTH a person don’t use top hat.

From the information on the question we have 4 options with their respective probability:

1. A person could be rascal and use top Hat: this probability is calculate as the multiplication of the probability of be a rascal (0.5) and use a top hat (0.9), then:

P(R y TH)=0.5*0.9=0.45

2. A person could be rascal and don’t use top Hat: this probability is calculate as the multiplication of the probability of be a rascal (0.5) and not use a top hat (0.9), then:

P(R y NTH)=0.5*0.1=0.05

3. A person could be not rascal and use top Hat: this probability is calculate as the multiplication of the probability of not be a rascal (0.5) and use a top hat (0.3), then:

P(RC y TH)=0.5*0.3=0.15

4. A person could be not rascal and not use top Hat: this probability is calculate as the multiplication of the probability of not be a rascal (0.5) and not use a top hat (0.7), then:

P(RC y NTH)=0.5*0.7=0.35

Then the probability that a person is a rascal given that he is wearing a top hat could be written and calculate as:

$P(R/TH)=\frac{P(R y TH)}{P(TH)}$

For calculate P(TH) we need to sum all the option in which TH is involve so:

P(TH) = P(R y TH)+ P(RC y TH)

P(TH)=0.45+0.15=0.6

Replacing values on the first equation we get:

$P(R/TH)=\frac{0.45}{0.6} =0.75$

So, the probability that a person is a rascal given that he is wearing a top hat is 0.75

5 0

3 years ago

Seventh grade > EE.11 Probability of independent and dependent events NED

ella [17]

Step-by-step explanation:

each combination of 2 specific numbers has the same probability. there is no difference in probability between the individual numbers.

remember, a probability is always desired cases over all possible cases.

we have 4 different possible outcomes every time we spin the spinner.

to get a specific number has the probability of 1/4, because we want 1 specific outcome, and have in total 4 different possibilities.

now, we spin a second time. the probability to get a specific number is again 1/4.

but, if we consider both events to be connected, when we want to know the probability to get 2 specific numbers when spinning twice, we have to multiply the individual probabilities :

1/4 × 1/4 = 1/16

so, the probability to land first on a 5, and then secondly on a 2 is 1/16.

the same as for landing first on a 3, and then on a 5.

the same as for landing first on a 4, and then on a 4 (again).

that is because the individual spin results are independent. the result of the first spin does not impact in any way the result of the second spin (in contrary to e.g. pulling multiple cards without returning the previously pulled cards).

8 0

2 years ago