Here are the numbers rounded to one decimal place:

a) 27.564 → 27.6 (since 6 is greater than 5, we round up)
b) 978.299 → 978.3 (since 9 is greater than 5, we round up)
c) 42.935 → 42.9 (since 3 is less than 5, we round down)
d) 8.99 → 9.0 (since 9 is greater than 5, we round up)

Would you like a detailed explanation of rounding rules?

Related Questions:

1. How do you round to two decimal places?
2. What is the difference between rounding and truncating?
3. How do you round negative numbers?
4. Why do we round numbers in mathematics?
5. How does rounding affect accuracy in real-world applications?

Tip: Always look at the digit immediately after the place value you are rounding to before making a decision.