surface area and volume
posted by lilman on .
I really need some help, I don't fully understand. Exspecially with fractions, don't know how to enter them on calculator.
1. What is the approximate volume of the sphere?
524 m³ (my choice)
1,000 m³
1,256 m³
1,570 m³
2. What is the approximate surface area of the sphere?
225 yd2
707 yd2
1,767 yd2 (my choice)
5,301 yd2
3. What is the approximate volume of the sphere if the surface area is 482.8 mm²?
998 mm³
1,126 mm³
2,042 mm ³
2,993 mm³
I don't understand this one.
4. What is the approximate surface area of the sphere?
342.3 km2
451.9 km2
903.4 km2
2,713 km2
Don't understand.
5. What is the approximate radius of a sphere whose volume is 1,349 cm³?
5.7 cm
6.9 cm
11 cm
14.7 cm
Don't understand.

you are dealing with two equations
1. surface area of sphere = 4π r^2
2. volume of sphere = (4/3)π r^3
notice all you need is the radius.
Since we cannot see your diagrams, #1, and #2 cannot be checked
3. given 4πr^2 = 482.8
r^2 = 482.8/(4π) = 38.42
r= √38.42 = 6.198
volume = (4/3)πr^3 = 997.53 , looks like a)
4.
you must have the radius given to you, just plug into the formula
5.
(4/3)πr^3 = 1349
r^3 = 1349/((4/3)π) = 322.05
r= (322.05)^(1/3) , the cube root of 322.05
= 6.85 (looks like b) )
fractions are really just divisions
e.g. 3/4 = 3 ÷ 4 = .75
you calculator should have a key for π
for powers look for key such as y^{x} or a variation of that
to do 322.05^(1/3) I entered
322.05
y^{x}
(1/3)
=
to get 6.85447... 
number 2 is wrong its b. 707 yd^2.

1. 524 m^3 (A)
2. 707 yd^2 (B)
3. 998 mm^3 (A)
4. 451.9 km^2 (B)
5. 6.9 cm (B) 
I got a 5/5. Go Mariners!

"Hannah is right" was correct!

"Hannah is right" Is 100% right!

god bless "hannah is right"
100 percent correct ;) 
thanks hannah you're 100% correct i got a 5/5 100%