Isobel consumes positive quantities of both jam and juice. The price of jam is 10 cents per unit and the price of juice is 5 cents per unit. Her marginal utility of jam is 12 and her marginal utility of juice is 6.
A) Without changing her total expenditures, she could increase her utility by consuming more jam and less juice
B) Without changing her total expenditures, she could increase her utility by consuming more juice and less jam
C) Without changing her total expenditures on jam and juice, she could not increase her utility
D) She should spend more money on both jam and juice.
If two goods are perfect substitutes,
A) there is a bliss point and the indifference curves surround this point.
B) straight indifference curves have a negative slope.
C) convex indifference curves have a negative slope.
D) indifference curves have a L-shape.
The consumer is in equilibrium when
A) MRT MRS
B) Px/Py MUx/MUy.
C) the budget line is tangent to the indifference curve at the bundle chosen.
D) All of the above.

Isobel can increase her total utility by consuming more of jam and less of juice. Her total expenditure will not change and therefore price of jam is 10 cents while price of juice is 5 cents. She can have more jam because marginal utility for jam is double than juice.