If you do 38 -7x2 you can work out the combined ages of them now which is 24 (you have to do 7x2 because there are two of them and its seven years in the future). Then you can work out their ages using a ratio. Dave’s age : his sister’s age is 3:1 so if you divide 24 by 4 (3+1 = 4 so your can work out one portion of their age) you can find out how old the sister is which is 6. Times that by 3 to get Dave’s age which is 18. A formula for this (where x is his sisters age) would be 3x=38-7x2 which cancels down to 6.

7 0

3 years ago

Help ASAP! 20 Points!

ANTONII [103]

Volume of cylinder is 3 times of volume of cone having same base diameter and same height.

Solution:

Given that

A cylinder and A cone have the same diameter = 10 inches and same height = 12 inches

Need to find the relationship between volume of cylinder and cone.

Let’s calculate volume of each object separately first.

Calculation of volume of cylinder :

Formula of volume of cylinder is given as:

$V_{c y}=\pi r^{2} h$

Where π=3.14

$\text { radius } r=\frac{\text {diameter}}{2}=\frac{10}{2}=5 \text { inches }$

height h = 12 inches

On substituting given values in formula of cylinder we get

$\begin{array}{l}{V_{c y}=3.14 \times 5^{2} \times 12=942 \text { cubic inches }} \\\\ {\text { Volume of cylinder }=V_{c y}=942 \text { cubic inches }}\end{array}$

Calculation of volume of cone:

Formula of volume of cone is given as:

$V_{c o}=\frac{\pi r^{2} h}{3}$

Here π=3.14

$\begin{array}{l}{\text { radius } r=\frac{\text { diameter }}{2}=\frac{10}{2}=5 \text { inches }} \\\\ {\text { height } \mathrm{h}=12 \text { inches }}\end{array}$