Answer:
Differences=

Step-by-step explanation:
Volume of first box=15cm×4cm×8cm

Volume of second box=10cm×9cm×4cm

Answer: 40km/h
Step-by-step explanation:
distance = 20km
time = 30 min conver to hours. 
velocity = ?


Since

, and you have a corresponding term in the given Riemann sum of

, you know the integral is being taken over an interval of length 5, so you can omit the second choice.
Next,

corresponds to

with

. The fact that

alone tells you that the interval of integration starts at 3, and since we know the interval has length 5, that leaves the first choice as the correct answer.
Answer:
2 hours.
Step-by-step explanation:
8 hours x 25 / 100 = 2 hours