April 2025
Problem of the Month
Elon Musk
From Kate Neill and Ray Frantz
There are two problems relating to Elon Musk. Solve either one for credit; solve both for extra credit!
Many thanks to Kate Neill and Ray Frantz for their ideas for these problems.
(1) With Donald Trump's return to the White House and his campaign promises to cut regulations and lower taxes, many anticipated that 2025 would be a banner year for billionaires.
However, market volatility in the wake of new tariffs and mounting concerns over a U.S. recession have created uncertainty in the U.S. economy.
As of Monday, March 10, 2025 the world's richest person, Elon Musk, had lost $132 billion this calendar year and now has a net worth of $301 billion.
But not to worry. Even with a net worth of "only" $301 billion left, Musk should be able to live comfortably for the rest of his life. How well?
Let's calculate.
As of 11 March 2025, Musk was 53 years old. He was born on 28 June 1971. If Musk lives to his biblical "three-score-and-ten" (i.e., 70 years) and dies on his birthday at age 70,
how much of his net worth would Musk have to spend each day from 11 March 2025 until his death in order to have no net worth when he died?
Don't forget to calculate leap years!
(2) On January 21, 2025, Tesla stock was trading at $424.07 on the stock market. One month later, on February 21, Tesla stock had fallen to $337.80.
If the stock continued to fall at the same monthly percentage rate, in what month and year would the Tesla stock be worth less than a dollar?
In the problem, the stock would be worth $269.08 on March 21, 2025 -- this is a check to see if you are doing the problem correctly
(FYI: the actual value of Tesla stock on March 10 was $222.15 but this has nothing to do with the problem).