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3 years ago

Marcel made an error when he used the distributive property to solve the problem shown. Which sentence describes the error?

Mathematics

2 answers:

Phoenix [80]3 years ago

7 0

The answer to this is step 2 because they multiplied when they should of subtracted the 10 and the 12.

Darya [45]3 years ago

5 0

Answer:

In Step 2, 90 should be multiplied by the quantity 10 – 12, not by 10.

Step-by-step explanation:

Consider the provided expression.

$90\cdot x-90\cdot 12$ when x=10

Solve the above expression as shown:

Step 1:

$90\cdot x-90\cdot 12=90(x-12)$

Step 2: Substitute x=10.

$90\cdot x-90\cdot 12=90(10-12)$

Step 3: Open the parenthesis.

$90\cdot x-90\cdot 12=900-1080$

Step 4: Simplify

$90\cdot x-90\cdot 12=-180$

From the above calculation we can say that the error is:

In Step 2, 90 should be multiplied by the quantity 10 – 12, not by 10.

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Suppose I ask you to pick any four cards at random from a deck of 52, without replacement, and bet you one dollar that at least

Tatiana [17]

Answer:

a) No, because you have only 33.8% of chances of winning the bet.

b) No, because you have only 44.7% of chances of winning the bet.

Step-by-step explanation:

a) Of the total amount of cards (n=52 cards) there are 12 face cards (3 face cards: Jack, Queen, or King for everyone of the 4 suits: clubs, diamonds, hearts and spades).

The probabiility of losing this bet is the sum of:

- The probability of having a face card in the first turn

- The probability of having a face card in the second turn, having a non-face card in the first turn.

- The probability of having a face card in the third turn, having a non-face card in the previous turns.

- The probability of having a face card in the fourth turn, having a non-face card in the previous turns.

1) The probability of having a face card in the first turn

In this case, the chances are 12 in 52:

$P_1=P(face\, card)=12/52=0.231$

2) The probability of having a face card in the second turn, having a non-face card in the first turn.

In this case, first we have to get a non-face card (there are 40 in the dech of 52), and then, with the rest of the cards (there are 51 left now), getting a face card:

$P_2=P(non\,face\,card)*P(face\,card)=(40/52)*(12/51)=0.769*0.235=0.181$

3) The probability of having a face card in the third turn, having a non-face card in the first and second turn.

In this case, first we have to get two consecutive non-face card, and then, with the rest of the cards, getting a face card:

$P_3=(40/52)*(39/51)*(12/50)\\\\P_3=0.769*0.765*0.240=0.141$

4) The probability of having a face card in the fourth turn, having a non-face card in the previous turns.

In this case, first we have to get three consecutive non-face card, and then, with the rest of the cards, getting a face card:

$P_4=(40/52)*(39/51)*(38/50)*(12/49)\\\\P_4=0.769*0.765*0.76*0.245=0.109$

With these four probabilities we can calculate the probability of losing this bet:

$P=P_1+P_2+P_3+P_4=0.231+0.181+0.141+0.109=0.662$

The probability of losing is 66.2%, which is the same as saying you have (1-0.662)=0.338 or 33.8% of winning chances. Losing is more probable than winning, so you should not take the bet.

b) If the bet involves 3 cards, the only difference with a) is that there is no probability of getting the face card in the fourth turn.

We can calculate the probability of losing as the sum of the first probabilities already calculated:

$P=P_1+P_2+P_3=0.231+0.181+0.141=0.553$

There is 55.3% of losing (or 44.7% of winning), so it is still not convenient to bet.

5 0

4 years ago

PLEASE HELP ME!!!!!!

Sonja [21]

Answer:

$\huge \red{ c_3 = - 1}$

Step-by-step explanation:

$c_1 = 1 \\ \\ c_n= - 2c_{n-1}+5 \\ \\ c_2 = - 2c_{2-1}+5 \\ \\ c_2 = - 2c_{1}+5 \\ \\ c_2 = - 2(1)+5 \\ \\ c_2 = - 2+5 \\ \\ \huge \purple{c_2 =3} \\ \\ c_3 = - 2c_{3-1}+5 \\ \\ c_3 = - 2c_{2}+5 \\ \\ c_3 = - 2(3)+5 \\ \\ c_3= - 6+5 \\ \\ \huge \red{ c_3 = - 1}$

6 0

3 years ago

A school bought 32 new desks. Each desk cost $24. Estimate how much the school spent on the new desks.

Pavlova-9 [17]

Estimate:

32 x 24

30 x 25

$750

8 0

3 years ago

Read 2 more answers

An electronics store received two shipments of radios. Of the 250 radios in the first shipment, exactly 6% were damaged. In the

nataly862011 [7]

Answer:

Total number of not damaged = 451

C. 451

Step-by-step explanation:

In the first shipment, 6% of the 250 radios where damaged.

Number of damaged= 6/100 * 250

Number of damaged= 6*2.5

Number of damaged= 15 radios.

Number of not damaged= 250-15

Number of not damaged = 235 radios

In the second shipment, 4% of the radios were damaged

Let the number of second shipment= y

0.04 of y where damaged

Total number of radio damaged= 24

15 + 0.04y = 24

0.04y= 24-15

0.04y = 9

Y= 9/0.04

Y= 225

Number of radio in the second shipment= 225

Number of damaged in the second shipment= 0.04*225

Number of damaged in the second shipment= 9

Number of not damaged in the second shipment= 225-9

Number of damaged in the second shipment= 216

Total number of not damaged

= 235+216

= 451

Total number of not damaged= 451

7 0

3 years ago

Mr.Eastman drew triangle JKL,with a height of 12 inches and a base of 12 inches, and triangle XLZ, with a height of 8 inches and

34kurt

Answer:

Step-by-step explanation:

Area of triangle = 1/2 × Base × Height

Mr.Eastman drew triangle JKL,with a height of 12 inches and a base of 12 inches

Area of JKL = 1/2 × 12 inches × 12 inches

= 72 Square inches

triangle XLZ, with a height of 8 inches and a base of 16 inches. Which triangle has the greater area?

5 0

3 years ago