By how much did the price of one gram of gold change from the beginning of week 1 to the end of the week 4? Did the price increase or decrease?

the complete question in the attached figure

we know that
Part a):
From the table,
iweek 1, the price increased by $1.25,
iweek 2, the price decreased by $3.125,
week 3, the price increased by $0.625
week 4, the price increased by $1.5
After the 4 week the change in price is given by
1.25 - 3.125 + 0.625 + 1.5 = 0.25.
Therefore

the answer Part a) is
the price changed over the 4 weeks period by $0.25.

Part b):
After the 4 week the change in price is given by
1.25 - 3.125 + 0.625 + 1.5 = 0.25
0.25  > 0
Therefore, 

the answer part B) isthe price increased over the 4 weeks period.

Part c)Given that the price of 1 gram of gold was $39.28 at the end of week 4.
and
 the price of 1 gram of gold increased by $0.25 over the 4 weeks period,
thus
 the price of 1 gram of gold at the beginning of week 1 is given by:
39.28 - 0.25 = $39.03

the answer Part C) is
the price of 1 gram of gold at the beginning of week 1 is $39.03