A certain household has consumed 250 units of energy during a month. How much energy is this in joules?

1 unit of energy is up to one B.T.U. (kWh).

1 unit = one kWh

\( 1 \ kWh \ = \ 3.6 x 10^6 \ J \)

\(\therefore \) 250 units of energy
= \( 250 \ × \ 3.6 × 10^6 \)

\( Energy \ = \ 9 × 10^8 \ J \) .