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2 years ago

Why do you cross-multiply when you solve proportions?

Mathematics

2 answers:

olga55 [171]2 years ago

4 0

Answer:

Step-by-step explanation:

since the cross multiples are equal, you find a product and use the inverse operation as you would in an equation

Example 4 is to 36 as 3 is to X: 4/36 = 3/X --> 4*X = 3*36. Divide both sides by 4, to solve for X = 27.

is over of = percent of 100

is/of=%/100

What is 10% of 40.

is = x

x/40 = 10/100

cross mulitply 40*10= 400/100=4 x=4

Dmitriy789 [7]2 years ago

3 0

When students cross multiply while solving a proportion, they are really multiplying both sides of the equation by the products of the two denominators. What happens is that each denominator cancels one of the factors on each side, so that it seems as if you have just crossed multiplied

Hope this helps!

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Which of the following will NOT improve your credit score?

Law Incorporation [45]

A. Taking out a new car loan

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2 years ago

In an effort to determine whether any correlation exists between the price of stocks of airlines, an analyst sampled six days of

vovikov84 [41]

Answer:

Check the explanation

Step-by-step explanation:

Following table shows the calculations:

Delta, X Southwest , Y X^2 Y^2 XY

45.96 38.76 2112.3216 1502.3376 1781.4096

46.8 45.41 2190.24 2062.0681 2125.188

47.93 15.7 2297.2849 246.49 752.501

51.78 49.58 2681.1684 2458.1764 2567.2524

52.17 44.34 2721.7089 1966.0356 2313.2178

47.36 18 2242.9696 324 852.48

Total 292 211.79 14245.6934 8559.1077 10392.0488

Sample size: n =6

Now

$S_{yy}=\sum y^{2}-\frac{\left (\sum y \right )^{2}}{n}=1083.27$

$S_{xx}=\sum x^{2}-\frac{\left (\sum x \right )^{2}}{n}=35.03$

$S_{xy}=\sum xy-\frac{\left (\sum x \right )\left (\sum y \right )}{n}=84.94$

The coefficient of correlation is :

$r=\frac{S_{xy}}{\sqrt{S_{xx}S_{yy}}}=0.436$

7 0

3 years ago

If Kendra started working at 10:30 a.m. and left at 6:15 p.m., how many hours of work should she record for the day on her time

Tom [10]

<span>From 12 PM to 6 PM is 6 hours From 11 AM to 12 PM is 1 hour We are left with 30 minutes (from 10:30 AM to 11 AM) + 15 minutes (from 6 PM to 6:15 PM), so total time (add up what we have) is 7 hours and 45 minutes.</span>

3 0

2 years ago

Read 2 more answers

I need help with this please....Thanks

IrinaK [193]

Answer:

The total cost of redecoration is £66, that is less than £75. Tenant can decorate the room for the budget set.

Step-by-step explanation:

Lets start calculating the areas of shorter and longer walls.

The area of shorter wall is

2.65m*2.98m=7.897m^2.

The area of longer wall is

3.94m*2,65m=10.441m^2.

Together the area of one long and one short wall is

7.897m^2+10.441m^2=18.338m^2.

The area to be painted ( one short and one long wall) is 18.338m^2 that is less than 30m^2, and hence only one tin of paint is needed (costs £16).

If there is assumed that the sheets of wallpaper must be whole from floor to ceiling, the calculations are following.

We get from one roll

10m/2.65m=3.77 sheets; we can use only 3 of them

The width of the walls is 3,94m+2,98m=6,92m,

and division gives 6.92m/0.52m=13,3... .

Hence it requires 14 sheets, that is 5 rolls of wallpaper.

Wallpaper costs 5*£10=£50 and altogether it is needed £50+£16=£66 to redecorate the room.

7 0

3 years ago

A Cab charges $1.75 for the flat fee and $0.25 for each mile. Write and solve an inequality to determine how many miles Eddies c

NemiM [27]

1.75 + 0.25x ≤ 15
where x is equal the number of miles.

The key to solving an inequality is just temporarily making the ≤ symbol a =. Then solve for x like any other algebraic equation. Once you find the value of x, you will have solved the inequality. Make sure to add back the ≤ when you are done.

15 - 1.75 = 13.25
13.25/0.25 = x
x = 53
add back the ≤
x ≤ 53
This means Eddies can travel up to 53 miles with his $15.

4 0

3 years ago