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Stels [109]
3 years ago
10

A rectangular prism has a base area of 56 square feet and a volume of 840 cubic feet. The length of the base is longer than the

width. If the sum of the length and width of the base is equal to the height of the pyramid, what is the length of the base in feet?
Mathematics
1 answer:
katovenus [111]3 years ago
6 0
The answer is 8 ft.

The base area of rectangular prism is: A = l * w = 56 ft²
<span>The length of the base is longer than the width: l > w

The volume of the prism is: V = l * w * h = 840 ft</span>³
<span>The sum of the length and width of the base is equal to the height of the pyramid: l + w = h

So:
</span>l * w = 56
l * w * h = 840
___
56 * h = 840
h = 840 / 56
h = 15 ft

Now, we know that
l + w = 15         ⇒ w = 15 - l
l * w = 56
___
l * (15 - l) = 56
15l - l² = 56
0 = l² - 15l + 56

Or: l² - 15l + 56 = 0

Let's solve the quadratic function:
l = (-b +/-√(b² - 4ac)/(2a)
  = (15 +/-√(-15)² - 4 * 1 * 56))/(2*1)
  = (15 +/- √(225 - 224))/2
  = (15 +/- √1)/2
  = (15 +/-1)/2
 
l = (15+1)/2 = 16/2 = 8
or
l = (15-1)/2 = 14/2 = 7

If l = 8, then w = 15 - 8 = 7.    So, l > w
If l = 7, then w = 15 - 7 = 8.     So, l < w

Therefore, l = 8 ft.
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25% of what number is 50?
LekaFEV [45]

Answer:

200

Step-by-step explanation:

The unknown number = x

25% of x = 50

25% of x = 0.25x

0.25x = 50

Multiply both sides of the equation by 4

x = 200

Hope this helps :)

5 0
2 years ago
1.)Find the height of a rectangular prism if the surface area is 148 cm2, the width is 4 cm and the length is 5 cm.
Contact [7]
1) surface of a rectangular prism=2(length x width)+2(length x height)+2(width x height)

Therefore:
148 cm²=2(5 cm x 4 cm)+2(5 cm x h)+2(4 cm x h)=
148 cm²=40 cm²+10 cm h+8 cm h
18 cm h=148 cm²-40 cm²
18 cm h=108 cm²
h=108 cm² / 18 cm=6 cm.

answer: height=6 cm 

2)
Volume of a rectangular prism= length x width x height 
therefore:
34 cm³=(1.7 cm)(0.5 cm) h
0.85 cm² h=34 cm³
h=34 cm³/0.85 cm²
h=40 cm.

answer: height=40 cm

3)
volume of a cylinder: πr²h
therefore.
118.79 ft³=πr²(5 ft)
r=√(118.79 ft³/5π ft)≈2.75 ft

answer: radius=2.75 ft

4)
 
Surface area of the pyramid with square base=4(A side)+A base
A side=(1/2)(8ft)(12 ft)=48 ft²
A base=(8 ft)(8 ft)=64 ft²

surface area=4(48 ft²)+64 ft²=256 ft²

Answer: the surface area of this pyramid would be 256 ft².

5)
surface of a cone=πrs+πr²
therefore:
radius=diameter/2=6.2 ft/2=3.1 ft
63.3 ft²=π(3.1 ft) s+π(3.1 ft)²
3.1π ft s=33.109 ft²
s=33.109 ft² /3.1π ft
s≈3.4 ft

Answer: the slant height would be 3.4 ft.

6)
volume of a square pyramid=(area of base x heigth)/3
therefore:
area of base=(6 ft)(6 ft)=36 ft²
126.97 ft³=36 ft² h /3
h=126.97 ft³/12 ft²=10.58 ft

answer: the height would be 10.58 ft.

7)
volume of a cone =(base x height)/3
base of a cone=πr²
therefore: 
199.23 cm³=πr²(9 cm)/3
r=√(199.23 cm³ / 3π cm)≈4.6 cm

answer: the radius would be 4.6 cm.

5 0
2 years ago
A restaurant has a total of 30 tables which are of two
Anna007 [38]

Answer:

Total number of tables of first type       = 23.

Total number of tables of second type = 7

Step-by-step explanation:

It is given that there are 30 tables in total and there are two types of tables.

Let's call the two seat tables, the first type as x and the second type as y.

∴                                             x + y = 30                        ......(1)

Also a total number of 81 people are seated. Therefore, 2x number of people would be seated on the the first type and 5y on the second type. Hence the equation becomes:

                                            2x + 5y = 81                        .....(2)

To solve (1) & (2) Multiply (1) by 2 and subtract, we get:

                                                      y = 7

Substituting y = 7 in (1), we get x = 23.

∴ The number of tables of first kind         = 23

  The number of tables of second kind   = 7

3 0
2 years ago
29.8725 rounded to the nearest hundredth
Alex Ar [27]

Answer:

29.87

Step-by-step explanation:

4 0
2 years ago
Question from my math test
frutty [35]

Answer:

The manager skipped June

Step-by-step explanation:

In the first bar we can see the sales are from

January - February

Then,

March - April.

But then, the store manager goes from

May - July,

and totally skipped June, therefore making it look like the sales have increased.

4 0
2 years ago
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