Plz help it’s due tomorrow

(a) Suppose you have 9 gold coins that look identical, but you also know one (and only one) of them is counterfeit. The counterf

alisha [4.7K]

Answer:

Step-by-step explanation:

You can split the coins into 3 groups, each of them has 3 coins. Weigh group 1 vs group 2, if one is lighter, that group has the fake coin. If both groups weigh the same, then group 3 has the fake coin.

Continue to split the group that has the fake coin into 3 groups, each group has 1 coin. Now apply the same procedure and we can identify the fake coin.

Total of scale usage is 2

b) if you have $3^n$ coins then you can apply the same approach and find the fake coin with just n steps. By splitting up to 3 groups each step, after each step you should be able to narrow down your suspected coin by 3 times.

Step 1: you narrow down to group of $\frac{3^n}{3} = 3^{n-1}$ coins

Step 2: you narrow down to group of $\frac{3^{n-1}}{3} = 3^{n-2}$ coins

Step 3: you narrow down to group of $\frac{3^{n-2}}{3} = 3^{n-3}$ coins

...

Step n: Step 1: you narrow down to group of $3^{n-n} = 3^0 = 1$ coin

8 0

3 years ago

The points (-7,-8) and (8,-8) fall on a particular line. What is its equation in slope-intercept form?

stepan [7]

Y=-8 because there is no slope

7 0

3 years ago

teh table shows a number of balls that fit into containers each container holds the same amount of balls

Paladinen [302]

Answer:

4

Step-by-step explanation:

all the containers seem to have 1/2 of the balls

6 0

3 years ago

Find the area of a circle with radius 6m use the value 3.14

Umnica [9.8K]

Area= 3.14 x 6squared
= 113.04m

6 0

4 years ago

Read 2 more answers

Two cars simultaneously left Points A and B and headed towards each other, and met after 2 hours and 45 minutes. The distance be

Oksana_A [137]

<h2>Hello!</h2>

The answers are:

$FirstCarSpeed=41mph\\SecondCarSpeed=55mph$

To calculate the speed of the cars, we need to write two equations, one for each car, in order to create a relation between the two speeds and be able to calculate one in function of the other.

So,

Tet be the first car speed "x" and the second car speed "y", writing the equations we have:

For the first car:

$x_{FirstCar}=x_o+v*t$

For the second car:

We know that the speed of the second car is the speed of the first car plus 14 mph, so:

$x_{SecondCar}=x_o+(v+14mph)*t$

Now, from the statement that both cars met after 2 hours and 45 minutes, and the distance between to cover (between A and B) is 264 miles, so, we can calculate the relative speed between them:

If the cars are moving towards each other the relative speed will be:

$RelativeSpeed=FirstCarSpeed-(-SecondCarspeed)\\\\RelativeSpeed=x-(-x-14mph)=2x+14mph$

Then, since we know that they covered a combined distance equal to 264 miles in 2 hours + 45 minutes, we have:

$2hours+45minutes=120minutes+45minutes=165minutes\\\\\frac{165minutes*1hour}{60minutes}=2.75hours$

Writing the equation:

$264miles=(2x+14mph)*t\\\\264miles=(2x+14mph)*2.75hours\\\\2x+14mph=\frac{264miles}{2.75hours}\\\\2x=96mph-14mph\\\\x=\frac{82mph}{2}=41mph$

So, the speed of the first car is equal to 41 mph.

Now, for the second car we have that:

$SecondCarSpeed=FirstCarSpeed+14mph\\\\SecondCarSpeed=41mph+14mph=55mph$

We have that the speed of the second car is equal to 55 mph.

Hence, the answers are:

$FirstCarSpeed=41mph\\SecondCarSpeed=55mph$

Have a nice day!

7 0

3 years ago