Final answer:
To round 249,678 to the greatest place value, we increase the digit in the hundreds place by 1 to get 249,700. There are 2 zeros in the rounded number. The estimated speed of sound using a power of 10 can be 3 x 10^2 m/s.
Step-by-step explanation:
To round 249,678 to the greatest place value, we look at the digit to the left of the place value we want to round to. In this case, we want to round to the greatest place value, which is the hundreds of places. The digit to the left of the hundreds place is 6, which is greater than or equal to 5. Therefore, we increase the digit in the hundreds place by 1, making it 7. The other digits to the right of the hundreds place become zeros, so the rounded number is 249,700.
In the rounded number, there are 2 zeros since the hundreds place is followed by the tens place and then the ones place and the rest of the digits are zeros.
The estimated speed of sound using a power of 10 can vary depending on the context. For example, using a power of 10, the speed of sound can be estimated as 3 x 10^2 m/s, which is 300 m/s. However, it's important to note that the actual speed of sound is approximately 343 m/s at room temperature.