Answer:
1.2
Step-by-step explanation:
A line over a number indicates that it is the last significant figure in a measurement.
It is difficult in ordinary typing to put a line over a digit, so I will use an underline instead.
A common rule is that the square root of a number contains the same number of significant figures as are in the number itself.
In all operations, you should carry one extra digit as a guard digit, to avoid roundoff errors.
Then,
√0.9 = 0.95
-√2.7 = -1.64
+√1.7 = 1.30
+√0.4 = 0.63
1.24
We round off the answer to one digit past the decimal point, so the final answer is 1.2.
