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3 years ago

Can someone please help me with these 3, 7th grade math homework word problems. I will give brainliest and obviously a thanks

Mathematics

1 answer:

NikAS [45]3 years ago

3 0

Answer:

Mia can spend no more than $55 at the mall. She buys a jacket for $23. Necklaces are on sale for $8. Find the amount of necklaces Mia can buy. Write and solve an inequality.

First, make the equation. She can't waste no more than(≥ or =) $55. And she already used $23.

55= 23+8(n)

n= number of necklaces she can buy.

Now, subtract 23 to both sides.

55= 23+8(n)

-23 -23

32= 8(n)

Then, divide by 8 to both sides to find how many necklaces she can buy.

32= 8(n)

8 8

4=n So, she can buy 4 necklaces.

A bag of marbles contains 3 red, 5 blue and 2 yellow marbles. What is the probability of choosing a blue marble and then choosing a red marble without replacement. Simplify the fraction.

First, add up the whole amount of marbles.

3+5+2= 10

This is very simple, to find the probability, just put...

number of blue marbles

total number of marbles

This gives you, 5/10 and simplified into 1/2.

For the red marble, do the same thing.

number of red marbles

total number of marbles

This gives you, 3/10 and it can't be simplified.

A football team loses 5 2/3 yards on the first play. On the next play, they gain 2 3/4 yards. What is the overall increases or decreases in yards?

For this word problem, add 2 3/4 yards to 5 2/3 yards to find the overall decrease or increase in yards.

Solve the whole number parts..

5-2= 3

Solving the fractions part...

2 - 3 = 8 - 9 = - 1

3 4 12 12 12

3- 1/12= 2 11/12

So, it was a 2 11/12 decrease.

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An urn contains 3 red and 7 black balls. Players A and B take turns (A goes first) withdrawing balls from the urn consecutively.

andrey2020 [161]

Answer:

The probability that A selects the first red ball is 0.5833.

Step-by-step explanation:

Given : An urn contains 3 red and 7 black balls. Players A and B take turns (A goes first) withdrawing balls from the urn consecutively.

To find : What is the probability that A selects the first red ball?

Solution :

A wins if the first red ball is drawn 1st,3rd,5th or 7th.

A red ball drawn first, there are $E(1)= ^9C_2$ places in which the other 2 red balls can be placed.

A red ball drawn third, there are $E(3)= ^7C_2$ places in which the other 2 red balls can be placed.

A red ball drawn fifth, there are $E(5)= ^5C_2$ places in which the other 2 red balls can be placed.

A red ball drawn seventh, there are $E(7)= ^3C_2$ places in which the other 2 red balls can be placed.

The total number of total event is $S= ^{10}C_3$

The probability that A selects the first red ball is

$P(A \text{wins})=\frac{(^9C_2)+(^7C_2)+(^5C_2)+(^3C_2)}{^{10}C_3}$

$P(A \text{wins})=\frac{36+21+10+3}{120}$

$P(A \text{wins})=\frac{70}{120}$

$P(A \text{wins})=0.5833$

6 0

3 years ago

One month Leila rented 3 movies and 2 video games for a total of $21 . The next month she rented 8 movies and 4 video games for

lina2011 [118]

x = price movie = 4.25
y = price game = 5.50

7 0

3 years ago

a football is fired upward with an initial speed of 800 feet per second. It is given that h=-12t^2+360t (h is the height of the

tangare [24]

Answer:

30 s

Step-by-step explanation:

When the ball hits the ground h=0. To find the time t when this happens we must solve the equation h=0.

●h= 0

● -12t^2+360t =0

● t(-12t +360) = 0

● t = 0 or -12t +360 =0

● t=0 or -12t = -360

● t=0 or 12t =360

● t=0 or t=360/12

● t=0 or t= 30

The equation has two solutions.

The ball was fired with an initial speed of 800 feet per second so it cannot hit the ground at t=0.

So the ball hits the ground after 30 s.

6 0

3 years ago

Find the total area the regular pyramid.

Ber [7]

Answer: $14\sqrt{3}$

Step-by-step explanation:

1. You must apply the following formula for calculate the total surface area the regular pyramid:

$SA=\frac{pl}{2}+B$

Where p is the perimeter of the base, l is the slant height and B is the area of the base.

2. The perimeter is, where s is the side length:

$p=3s=3*4=12$

3. The faces are isosceles traingles. So, to find the slant height you can divide one base into two equal right triangles and calculate the slant height with Pythagorean Theorem:

$l=\sqrt{4^2-2^2}=2\sqrt{3}$

4. The base is equal to any face, then both have equal areas. As previously you divide one base into two equal righ triangle to find the slant height, you can calcualte the area of one right triangle and multply it by 2 to calculate B:

$B=2*\frac{bh}{2}=2*\frac{2\sqrt{3}}{2}=2\sqrt{3}$

Finally substitute values:

$SA=\frac{12*2\sqrt{3}}{2}+2\sqrt{3}=14\sqrt{3}$

6 0

3 years ago

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A Copy of machine produces 80 copies in 5 minutes. How many copies would be produced in 40 minutes?

BlackZzzverrR [31]

The answer would be 640. To find the number of how many copies are produced in 1 minute you have to write 80 divided by 5 which equals 16. Now you multiply 16 and the 40 minutes which gives you 640 copies.

6 0

3 years ago

Read 2 more answers