What was the rate of change

Beginning of day, the sum of stocks in Dow Jones was $10,335.24. At the end of the day, the sum of the stocks in the Dow Jones was $10,215.78. What was the rate of change of Dow Jones on this particular day?
A. 1.0%
B. -1.2%
C.-1.3%
D.1.2%

Change of stock = $10,215.78 - $10335.24 = -$119.46
Rate of change = -119.46/10335.24= -1.2% .........Ans (B)

(end value - start value) / start value

= (10,215.78 - 10,335.24) / 10,215.78

= −119.46 / 10,215.78

= −0.01169

= −1.169%


Answer: B. −1.2%

x + xy = z
x(1 + y) = z
1 + y = z/x
y = (z/x) - 1

y = (10215.78 / 10335.24) - 1

y = 0.98844148757068050669360363184599 - 1
y = -0.01155851242931949330639636815401

y = -1.2%