Rose Harrison and Clara Huizink Solutions for Exercise 9: Practice 2

Determine whether there is a relationship of direct proportion, inverse proportion or neither. Justify your answer. If there is a proportional relationship, find $k$. The perimeter $p$ of an equilateral triangle with side length $l$.

Determine whether there is a relationship of direct proportion, inverse proportion or neither. Justify your answer. If there is a proportional relationship, find $k$. The number of liters $n$ of paint needed to paint an area $A$, given that $3$ liters will paint a $15{ \mathrm{m}}^2$ area.

Determine whether there is a relationship of direct proportion, inverse proportion or neither. Justify your answer. If there is a proportional relationship, find $k$.

$y=4 x$ 

Determine whether there is a relationship of direct proportion, inverse proportion or neither. Justify your answer. If there is a proportional relationship, find $k$.

$y=\frac{3}{x}$ 

Determine whether there is a relationship of direct proportion, inverse proportion or neither. Justify your answer. If there is a proportional relationship, find $k$.

$y=\frac{x}{5}$ 

Determine whether the relationship between the distance and the time to see the lightning is proportional relationship. If the lightning strikes $5\mathrm{km}$ away. Find how long it takes to see the lightning. 

Determine whether the relationship between the distance and the time to hear the thunder is proportional relationship. If lightning strikes $5\mathrm{km}$ away. Find how long it takes to hear the thunder. 

The relationship between the time to see the lightning and the time to hear the thunder is directly proportional.  Justify your answer. Lightning strikes $5\mathrm{km}$ away such that time taken by us to see the lightning is $0.0000167\text{ seconds }$, and the time taken by us to hear the thunder is $14.7\text{ seconds }$. Hence, Verify these answers.