HELP: Quantification of an Odd "Lifetime Phenomenon"

#1
Hello all,

I'm an engineer/coder whose statistical-logic insights are good, but lacking.

I had a very strange incident today in my childhood home related to the operating lifetimes of water-heaters. I'll spare you the details, but my widowed Mother is I the process of CONSIDERING selling our family's home of 50-years. We are expecting some house-inspectors tomorrow, and the house's 18-year-old water-heater sprung a leak this morning. It had a warrantee-lifetime of 9-years. My brother and I immediately replaced this unit, and after his departure, I went to my Mother's detached cottage only to find ITS water-heater leaking as well. They were different models, but installed at the same time: an 18-year-old water-heater of less capacity with a 6-year warrantee.

I'd like to know what the probability of these two units failing within 24-hours of each other, or at least be pointed in the right direction WRT standard mathematical approach.

Please help me! I need some decent math to discount proposals that it's my Dad's ghost forbidding the sale.
 

Miner

TS Contributor
#2
How do you know that the water heater in the cottage had not been leaking slowly for months? The 24 hour connection is artificial because the first leak encouraged you to look at the second unit, which may have already been leaking for some time unnoticed.