The sum of 3.0478 and 4.92 is
, which have 5 significant digits.
<u>Step-by-step explanation:</u>
We have ,
and
. The significant digits of a number are digits that includes all digits except:
- All leading zeros. For example, "013" has two significant figures: 1 and 3;
- Trailing zeros when they are merely placeholders to indicate the scale of the number and ,
- Spurious digits introduced, for example, by calculations carried out to greater precision than that of the original data, or measurements reported to a greater precision than the equipment supports.
Here
and with significant digit rules
. Now, Sum of both numbers = 
⇒Sum of both numbers = 
⇒Sum of both numbers = 
∴ The sum of 3.0478 and 4.92 is
, which have 5 significant digits.
8(41) + 8(5)
328 + 8(5) (multiply 8 by 41)
328 + 40 (multiply 8 by 5)
= 368 (add)
X = (-18) × 4
X = -72
The cave is 72 feet below sea level.