Chloe and libby want to tie ryan to a bunch of approximately spherical helium balloons of diameter 0.3m. the volume of each balloon can be approximated using the formula 4r³. given that 1 litre of helium can lift 1g, and that ryan weighs 5 stone and 5lb, estimate how many balloons they need to make him float.

 Aproximately 2,525 balloons

Step-by-step explanation:

1. Find the volume of a balloon with the formula given in the problem, where is the radius (), then:

2. Convert the volume from m³ to lliters by multiplying it by 1,000:

3. You know that that 1 liter of helium can lift 1 gram and that Ryan weighs 5 stone and 5 pounds. So you must make the following conversions:

1 g=0.0022 lb

From 5 stones to pounds

4. Then Ryan's weigh is:

5lb+70lb=75lb

5. Then, if 1 liter of helium can lift 0.0022 lb, to lift 75 lb (which is the weight of Ryan) they need:

6. Then, to calculate the aproximated number of balloons they need to make him float (which can call ), you must  divide the liters of helium needed to lift the weight of Ryan by the volume of a balloon, then the result is:

≈2,525 balloons.

b. astronomers

this answer is !