Question

Think of three goods for which the demand is inelastic with respect to price. Do these goods ever go on sale? Does understanding the relationship between elasticity and total revenue help you understand why some goods go on sale and others don’t?

Answer 1

Inelastic demand is a minute change in demand with respect to change in price. Normally goods with inelastic demand are necessities with no alternatives. Some goods for which the demand is inelastic are water, salt, electricity and even medicine etc. These are the kinds of goods that never go on sale because their demand doesn't change much with response to price.
This can be known through the relationship between elasticity and total revenue.
If the price increases, but total revenue falls, the demand is elastic.
but if the prices increase, but total revenue also rises as the fall in quantity demanded decrease is low compared to rise in price . hence the demand is inelastic