Answer:
The percentage decrease = 0.9%
Explanation:
Using the formula
Percentage Decrease = [ (Initial Value - Final Value) / |Initial Value| ] × 100
= [(9.80 - 9.71 ) / (9.80)] × 100
= [0.09 / 9.80] × 100
= 0.009 × 100
= 0.9%
Therefore, the percentage decrease = 0.9%