If government expenditure rises by $$27\mathrm{.}5$ billion and the multiplier in the economy is $2\mathrm{.}5,$ then:

real GDP rises by $$27\mathrm{.}5$ billion, and the IS curve shifts to the right.

real GDP falls by $$55$ billion, and the IS curve shifts to the left.

real GDP falls by $$11$ billion, but the IS curve does not shift.

real GDP rises by $$68\mathrm{.}75$ billion, and the IS curve shifts to the right.