To solve this guesstimate case, you need to determine the following:

• The number of people in the US
• The number of adults
• The number of wine drinkers
• Average number of glasses of wine consumed per week
• Number of glasses of wine in an average bottle

As an extra step, you can estimate how many wine bottles are used for such non-drinking purposes as cooking. This would earn you some brownie points.

Step 1: Clarify

Ask the interviewer whether he / she is referring to a standard-sized bottle of wine.

Step 2: Solve with the following assumptions:

There are about 300 million people in the United States.

20% of the population are minors who are legally not allowed to consume alcohol.

80% of the population are adults who are legally allowed to consume alcohol.

So, number of adults = 80% x 300 million = 240 million

Among the adults, let’s assume that 80% consume alcohol.

Number of adults consuming alcohol = 80% x 240 = 192 million

You can round up to this number to the nearest 100 to keep the math simple, say 200 million.

Among the 200 million that drink some alcohol, let’s assume that 75% drinks wine.

Number of adults that drink wine = 75% x 200 = 150 million

Let’s assume that on average, a wine drinker drinks two glasses of wine a week.

Number of glasses of wine / week = 2 x 150 million = 300 million glasses

Let’s assume that a wine bottle contains about five glasses of wine.

Number of bottles of wine = 300 million / 5 = 60 million

Let’s assume another 5 million bottles for non-drinking purposes, such as cooking.

In total, about 65 million bottles of wine are consumed per week in the US.