During a construction project, engineers used explosives to excavate 140 feet of tunnel into a mountain. But because of time constraints and environmental concerns, they brought in a tunnel boring machine (TBM) to excavate the rest of the tunnel. The data table lists some observations an engineer made about the length of the tunnel after the TBM was introduced.
How much of the tunnel was completed 26 days after the TBM was introduced?

1,170 feet

1,310 feet

1,260 feet

1,400 feet
TBM Use
(days)
(feet)
6 410
15 815
20 1,040
28 1,400
33 1,625
38 1,850
45 2,165

Question

During a construction project, engineers used explosives to excavate 140 feet of tunnel into a mountain. But because of time constraints and environmental concerns, they brought in a tunnel boring machine (TBM) to excavate the rest of the tunnel. The data table lists some observations an engineer made about the length of the tunnel after the TBM was introduced.
How much of the tunnel was completed 26 days after the TBM was introduced?

1,170 feet

1,310 feet

1,260 feet

1,400 feet
TBM Use
(days)	
(feet)
6	410
15	815
20	1,040
28	1,400
33	1,625
38	1,850
45	2,165

anonymous · Answer

20 days =1040     +6/8 of 360   because from 20 to 28 days 360 was excavated
26 days= 1040 +270=1310