More than 10% of Japan’s population is now age 80 or older, the government said Monday, the latest worrying milestone in the rapidly graying country’s demographic crisis.
“1 in 10 residents” does not refer to a person but a proportion of people, which is a plurality of people. Change it to “10% of residents” and it’s clear that 'are"is more gooder.
If you want to super expand it…
A proportion of 1 in 10 residents are…
Or
Proportionally 1 in 10 residents are…
Aaand also…
“are” acts on “residents”, not “1 in 10”. “1 in 10” is an adjective phrase. Residents is the noun.
“1 in 10 residents” does not refer to a person but a proportion of people, which is a plurality of people. Change it to “10% of residents” and it’s clear that 'are"is more gooder.
If you want to super expand it…
A proportion of 1 in 10 residents are…
Or
Proportionally 1 in 10 residents are…
Aaand also…
“are” acts on “residents”, not “1 in 10”. “1 in 10” is an adjective phrase. Residents is the noun.