Can someone help me with this?

Mathematics

1 answer:

Roman55 [17]2 years ago

7 0

Answer:

Step-by-step explanation:

We first need to figure out how much money Jackie has since Pilar has the same amount of money, but in different coins. Jackie has 24 dimes and 13 quarters, so the amount of money is $2.40 + $3.25 = $5.65; therefore, Pilar has $5.65 also. In order to determine how many nickels and quarters Pilar has, we have to have a system of equations. It's up to us to write the equations we need to solve this. The first equation has to do with the NUMBER of coins Pilar has, the second has to do with the VALUE of each coin. We know that Pilar has only nickels and quarters and that she has a total of 53 coins. So the NUMBER equation is

n + q = 53

The VALUE equation relates how much each coin is worth to the total amount of money it equals:

.05n + .25q = 5.65.

Go back to the first equation and solve it for either n or q. I solved it for n:

n = 53 - q

Plug this into the second equation in place of n now to get:

.05(53 - q) + .25q = 5.65 and

2.65- .05q + .25q = 5.65 and

.20q = 3 so

q = 15. This means that there are 15 quarters. If there are 15 quarters, then there are

n + 15 = 53 nickels and

n = 38 nickels.

You might be interested in

An hourglass consists of two sets of congruent composite figures on either end. Each composite figure is made up of a cone and a

belka [17]

Answer: third option 268.8

Explanation:

For this kind of proble it is very important that you attach the figure because it contains important information to understand the question.

I have attached the figure for better understanding.

1) The top portion (and the bottom is congruent but rotated 180°) of the hourglass is a figure equivalent to a cylinder on top and a cone on bottom.

So the total volume contained in the top portion is the volume of a cylinder + the volume of a cone.

This is how you calculate the volume of the top portion:

1) The height of the cylinder is 54 mm - 18 mm = 36 mm

2) The formula for the volume of a cylinder is V = π (radius)^2 * height

radius = 8 mm
height = 36 mm

=> V = π(8mm)^2 * 36 mm = 2304π (mm)^3

3) The formula for the volume of a cone is V = (1/3)π(radius)^2 * height

radius = 8 mm
height = 18 mm

V = (1/3)π(8mm)^2 * 18 mm = 384π (mm)^3

4) The total volume of the top portion is volumen of the cylindrical part + voume of the cone:

Total voluem = 2304π (mm)^3 + 384π (mm)^3 = 2688π (mm)^3

5) To find the number of seconds <span>it take until all of the sand has dripped to the bottom of the hourglass you have to divide the total volumen of sand by the rate:

time in seconds = total volume of sand / rate of dripping

time in seconds = [2688 π (mm)^3 ] / [10π (mm)^3 / s] = 268.8 s

That is the answer: 268.8 s
</span>