ANSWER
4.7 x 10³
Step-by-step explanation
To add these numbers we can write them without the scientific notation. To transform the first term, since the exponent of 10 is positive 3, we have to move the decimal point 3 places to the right,
In the second term, the exponent of 10 is negative 1, so we have to move the decimal point one place to the left,
And the last term doesn't have the multiplier. We did all this so that we can add these numbers directly because they all must have the same multiplier (the same exponent of 10),
To write this result in standard form, we have to move the decimal point so that there is only one digit to the left of the decimal point, and then round the other digits so that there are only 2 digits to the right of the decimal point. To keep the number the same, we multiply that by 10 raised to the number of places we move the decimal point: if we move it to the left the number is positive and if we move it to the right, the number is negative,
This has to be round to 2 significant figures, because the least amount of signigicTo round, we have to see what is the digit in the 2nd significant figure. If that digit is 5 or more, then we have to add 1 to the second significant digit. In this case, we have to add 1 to 6, because the 2nd digit is 9.
Hence, the result is 4.7 x 10³