Question

Pls answer Question 28 and 29 asap.

Answer 1

28. Answer: 86% decrease

Explanation:

Original Sphere has a radius of 100% → r =1

Surface Area of Original Sphere:

S.A. = 4πr²

= 4π(1)²

= 4π

New Sphere has a diameter of 75% → d = 0.75 → r = 0.375

Surface Area of New Sphere:

S.A. = 4πr²

= 4π(0.375)²

= 0.5625π

`\text{\% Change} =(New - Original)/(Original)\\\\.\qquad \qquad =(0.5625\pi -4\pi)/(4\pi)\\\\.\qquad \qquad =(-3.4375\pi)/(4\pi)\\\\.\qquad \qquad =-0.86`

The negative sign represents a decrease.

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29. Answer: 72 bottles

Explanation:

Volume of a hemisphere is:

`V=(2)/(3)\pi r^3\\\\.\quad =(2)/(3)\pi (18)^3\\\\.\quad = 3888\pi`

Volume of a cylinder is:

`V=\pi r^2h\\\\.\quad =\pi (3)^2(6)\\\\.\quad =54\pi`

The number of cylinders needed is:

`(3888\pi)/(54\pi) = 72`