[tex]\text{ 1.575}\times10^{10}\text{ liters of water will be n}eeded\text{ in a day}[/tex]
Explanation:
[tex]\begin{gathered} \text{World population = }3.15\times10^8 \\ \text{water consumption per person in a day = 50 liters} \end{gathered}[/tex][tex]\begin{gathered} \text{Total water consuption for the world population = y} \\ 50\text{ liters = 1 person} \\ y\text{ = 3.15}\times10^8 \\ \text{cross multiply:} \\ y(1)\text{ = 50(3.15}\times10^8) \\ y\text{ = 157.5 }\times10^8 \end{gathered}[/tex][tex]\begin{gathered} y\text{ = 1.575 }\times10^2\times10^8 \\ y\text{ = 1.575}\times10^{10} \\ \\ \text{ 1.575}\times10^{10}\text{ liters of water will be n}eeded\text{ in a day} \end{gathered}[/tex]