NeoPets Riddles (Lenny Conundrums) and Answers Here

And the corresponding number that you get you multiply by the lbs that each different substance weighs?

@plantgirl,

Yes, but I'll remind people that :
radius <> diameter, and
inch <> foot

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Wait, I figure the weight of each and subtract the weight of the smaller balls from the volume of the large sphere..right?

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Thanks! I did not take that into consideration!

Smile

1 Reply

@plantgirl,

Ah, I think you want to fix that - subtracting weight from volume makes no sense.

I calculated the total volume of steel and the total volume of water. I then multiplied each by the density to get the weights of each and added the weight of the steel and the weight of the water to get the total weight.

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@plantgirl,

Actually, I didn't until after submitting my answer, so no prize for me this week.

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Sorry I didn't ask sooner! Very Happy

1 Reply

@plantgirl,

Oh, I submitted my answer almost 45 minutes ago, but thanks.

1 Reply

Should the answer be in a number of pounds that would be logical for a planet (ie Neopia) or would it just be in consideration of water and steel?

2 Replies

@plantgirl,

One possible solution:

Radius of large sphere = 41/2*0.0833333333=1.708333327 foot

Thickness of steel = 0.8*0.0833333333=0.066666666 foot

Volume of large sphere = 4/3*pi*(1.708333327)^3 =20.88365207 cubic foot

Volume of large steel sphere = 20.88365207-4/3*pi*(1.708333327-0.066666666)^3=2.350745124 cubic foot

Radius of small sphere = 2/2*0.0833333333=0.0833333333 foot

Volume of a small steel sphere =4/3*pi*(0.0833333333)^3-4/3*pi*(0.0833333333-0.066666666)^3=0.002404675 cubic foot

Mass of steel spheres = (2.350745124+0.002404675*50)*490 = 1210.779669 lbs

Mass of water = (20.88365207 - 2.350745124 - 0.002404675*50)*62.4= 1148.950807 lbs

Total mass = 1210.779669 lbs + 1148.950807 lbs = 2360 lbs

Another possible solution:

Radius of large sphere = 41/2*0.0833333333=1.708333327 foot

Thickness of steel = 0.8*0.0833333333=0.066666666 foot

Volume of large sphere = 4/3*pi*(1.708333327)^3 =20.88365207 cubic foot

Volume of large steel sphere = 20.88365207-4/3*pi*(1.708333327-0.066666666)^3=2.350745124 cubic foot

Radius of small sphere = 2/2*0.0833333333=0.0833333333 foot

Volume of a small steel sphere =4/3*pi*(0.0833333333)^3=0.002404068 cubic foot

Mass of steel spheres = (2.350745124+0.002404068*50)*490 = 1211.254786 lbs

Mass of water = (20.88365207 - 2.350745124 - 0.002404068*50)*62.4= 1148.8903 lbs

Total mass = 1211.254786 lbs + 1148.8903 lbs = 2360 lbs

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@lennyfan,

Did anyone else get 4 digits with a sum of 13?

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I got 4 digits sum 18

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@Rab-Z,

i am pretty sure my solution is the right one =/ checked it couple of times

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@plantgirl,

It's only a model, so I wouldn't expect it to be a number of pounds sensible for a planet.

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@DDad,

Never mind, I got a different result that matched another given answer.

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@DDad,

I ended up with 4 digits and a sum of 11.

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@Kevin-vk-nguyen,

neopets does crazy stuff...you never no

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my digits equal 20

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correction 21

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what I did:

first I calculated the volume (in cubic feet) of the outer sphere
Secondly I calculated the volume of the inner sphere (diameter of 40.2 inch)

I substracted the outer sphere from the inner sphere and added the volume of 20 more solid spheres with a radius of 1 inch (offcourse also converted into feet)

The number I then got I multiplied by 490 and put in my memory.

I took the number from the inner sphere and substracted the volume of the 20 solid smaller spheres from it and that was my volume in water, which I multiplied by 62.4

then I added the two numbers up and I got to 4 digits sum 18

1 Reply

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