To solve 5/7 - 2/n = 1/21

For her presentation on the Wonders of the World, Mary baked a square pyramid-shaped cake as pictured below. The slant height of

mihalych1998 [28]

Answer:

$V=196in^3$

Step-by-step explanation:

The volume of a pyramid is:

$V=\frac{A_{b}h}{3}$

where $A_{b}$ is the area of the base and $h$ is the height (the perpendicular measurement between base and highest point, not the slant height)

Since the base is a square, the area is given by:

$A_{b}=l^2$

where $l$ is the length of the side: $l=8in$ , thus:

$A_{b}=(8in)^2\\A_{b}=64in^2$

Now we need to find the height, for this we use the right triangle that forms with half of a square side (8in/2 = 4in), the slant height (10in), and the height.

In this right triangle, the slant height is the hypotenuse, the leg 1 is the unknown height, and leg 2 is half of the square side.

Using pythagoras:

$hypotenuse^2=leg1^2+leg2^2$

substituting our values, and indicating that leg 1 is height h:

$(10in)^2=h^2+(4in)^2$

$100in^2=h^2+16in^2$

and solving for the height:

$h^2=100in^2-16in^2\\h^2=84in^2\\h=\sqrt{84in^2}\\ h=9.165in$

and finally we calculate the volume using this height and the area of the base:

$V=\frac{A_{b}h}{3}$

$V=\frac{(64in^2)(9.165in)}{3} \\V=195.5in^3$

rounding to the nearest cubic inch: $V=196in^3$

4 0

3 years ago

What is the value of x? Enter your answer in the box.

scoray [572]

Answer:

x=11

Step-by-step explanation:

Since the lines in the middle are parallel, we know that both sides are proportional to each other.

6:48 can be simplified to 1:8

Since we know the left side ratio is 1:8, we need to match the right side with the same ratio

We can multiply the ratio by 5 to match 5:3x+7

5:40

5:3x+7

Now we can set up the equation: 40=3x+7

Subtract 7 from both sides

3x=33

x=11

5 0

3 years ago

Solve each system by elimination. 10x-6y=-8 -10x+6y=8

Step2247 [10]

Answer:

Infinitely Many Solutions

Step-by-step explanation:

$10x-6y=-8\\-10x+6y=8\\\0 = 0\\$

4 0

2 years ago

Let’s assume the 147 freshman maintained a 65% attendance rate during the first 4 week of school. If our next 4 week goal for at

shutvik [7]

Answer:

12 students

Step-by-step explanation:

If 65% equals 147

Then to maintain 70% there is a need for 5% more

Which equals

5*147/65 ≈ 12 students

4 0

3 years ago

Read 2 more answers

John can jog twice as fast as he can walk. He was able to jog the first mile to his grandmas house but then he got tired and wal

statuscvo [17]

Answer:

12 mph

Step-by-step explanation:

The relationship between jogging speed and walking speed means the time it takes to walk 4 miles is the same as the time it takes to jog 8 miles. Then the total travel time (0.75 h) is the time it would take to jog 1+8 = 9 miles. The jogging speed is ...

(9 mi)(.75 h) = 12 mi/h . . . average jogging speed

__

Check

1 mile will take (1 mi)/(12 mi/h) = 1/12 h to jog.

4 miles will take (4 mi)/(6 mi/h) = 4/6 = 8/12 h to walk.

The total travel time is (1/12 +8/12) h = 9/12 h = 3/4 h. (answer checks OK)

_____

Comment on the problem

Olympic race-walking speed is on the order of 7.7 mi/h, so John's walking speed of 6 mi/h should be considered quite a bit faster than normal. The fastest marathon ever run is on the order of a bit more than 12 mi/h, so John's jogging speed is also quite a bit faster than normal. No wonder he got tired.

7 0

3 years ago