Final answer:
To write 7.7847 * 10^4 in standard notation with 2 significant figures, we round the number to 7.8 and move the decimal point 4 places to the right. The standard notation is 78,000.
Step-by-step explanation:
To write 7.7847 * 10^4 in standard notation with 2 significant figures, we need to round the number to 2 significant figures and move the decimal point accordingly. The two significant figures are 7 and 7.8, so the number should be rounded to 7.8. Since the exponent of 10 is positive 4, we need to move the decimal point 4 places to the right. Therefore, the standard notation is 78,000.