when it comes to addition of numbers the final answer should have the same number of decimal places as the least precise value or in other words the number with least number of decimal places
10.5 - has 1 decimal place
11.62 has 2 decimal places
add 10.5 + 11.62 = 22.12
the number with least number of decimal places is 10.5 with only 1 decimal place
therefore answer too should have 1 decimal place
22.12 rounded off to 1 decimal place is 22.1
answer is 22.1