On Monday, Joanna reads 3*16=<<3*16=48>>48 pages.
On Tuesday, Joanna reads 6.5 * 16 =<<6.5*16=104>>104 pages.
So far, she has read 48 +104 =<<48+104=152>>152 pages.
Thus, she has 248-152 = <<248-152=96>>96 pages left.
She will need to read for 96/16 = <<96/16=6>>6 hours to finish the book.
#### 6