Answer:
$8.77
Explanation:
Using the compound interest formula

A = amount compounded (in $)
P = Principal (in $)
r = rate (in %)
t = time it takes to accumulate fund (in years)
n = time of compounding (in years)
Given P = $10,000, r = 4%, t = 3.5 years n = 1/12 years (since it is compounded monthly)

Amount he will compound after 3.5years will be $11,211.1.
Amount he should invest daily = Amount compounded/time taken (in days)
Since 3.5years ≈ 1278 days
Amount he should invest daily = $11,211.1/1278
Amount he should invest daily = $8.77