Exploring maths through problem solving

Problem of the Week

Rainy Day Profits

A meteorologist tweeted that in the first 278 days of this year, Sydney has had 157 days with rain. This coffee shop sells umbrellas. If they buy umbrellas wholesale for $10 and on average, sell 5 umbrellas at $45 each on a rainy day (and none on other days), what annual gross profit will they make on the umbrellas if rainy days continue at the same rate for the rest of the year? 


There are several possible solution methods. This is the one I would use.

Profit per umbrella = $45 - $10 = $35

Number of rainy days in a year = 157 ÷ 278 x 365 = 206.133

Rounding the number of rainy days to 206 days:

Annual gross profit with 5 umbrellas sold per rainy day = $35 x 5 x 206 = $36 050.

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