Calculate Heat Flow Rate Across a Wall: 100 W Lightbulbs

[electritron]

Homework Statement

Two rooms, each a cube 3.8 m on a side, share a 12 cm thick brick wall. Because of a number of 100 W light-bulbs in one room, the air is at 27°C, while in the other room it is at 10°C. How many of the 100 W light-bulbs are needed to maintain the temperature difference across the wall? (Round your answer up to the nearest integer.)

Homework Equations

Q/t=kA(t₁-t₂)/l

The Attempt at a Solution

This looks so easy and I attempt to solve it and I get it wrong.
I used
Q/t=kA(t₁-t₂)/l
=(0.84J/s*m*C)(14.44m²)(27C-17C) / (0.12m)
=1718.36 then divide by 100 and it equals 17.1836=17
Do you have any ideas as to what I'm not comprehending because I'm sure this has to be the correct number of bulbs.

 

[Redbelly98]

Welcome to PF

The instructions say to round the answer up. Otherwise things look fine (assuming k is correct).