In the equation Q = a - bp + e; Q and P are .... Variables respectively.

Analyze the question: The equation Q = a − bP + e is a demand function (a simple regression-type equation). We need to say what kind of variable Q and P are, in that order.

Concept:

• Dependent variable: the variable whose value is determined by others (it appears alone on the left side).
• Independent variable: the variable that influences the dependent variable (it appears on the right side).
• Constants/parameters: a and b are fixed values (a is the intercept, b the slope).
• e: the error (disturbance) term.

Solution:

1. Q (quantity demanded) is on the left-hand side. Its value depends on the price, so Q is the dependent variable.
2. P (price) is on the right-hand side and determines Q, so P is the independent variable.
3. a and b are constants (parameters), and e is the error term. These are not what the question asks about.

So, in the order "Q and P respectively": dependent and independent.

Checking the options:

• A: Q is not a constant, so this is wrong.
• B: dependent and independent, which is correct.
• C: Q is not the error term, so this is wrong.
• D: Q is not independent and P is not a constant, so this is wrong.
• E: this is the reverse order, so it is wrong.

**Answer: B.

Tip: Look at which side of the equals sign the variable is on. The variable on the left, "Q = ...", is the one being explained (dependent). The variables on the right that explain it are independent. Also, watch the word "respectively", because it fixes the order of your answer.