Final answer:
The data type that stores data approximately is the float data type. Duration is quantitative continuous data. The mean or median can be appropriate measures of center depending on the data distribution, and the number of significant figures varies based on rules pertaining to zero placements.
Step-by-step explanation:
The data type that can only store data approximately is float. Floats are used to represent numbers that are not necessarily whole numbers and can have fractional parts. They are known as floating-point numbers because the decimal point can 'float'; that is, it can be placed anywhere relative to the significant digits of the number.
Duration (amount of time) is a type of quantitative continuous data because it can take on any value within an interval and is not limited to separate distinct values.
When examining the shape of data, if the data shows a symmetrical distribution, considering the mean as the most appropriate measure of center for the data might be more suitable. If the data is skewed or has outliers, the median is often a better choice because it is less affected by extreme values. The part of this question that refers to a continuous scale (c) would likely give a more suitable result for shape examination.
For determining the number of significant figures in measurements, the rules are as follows:
- Non-zero digits and zeros between non-zero digits are always significant.
- Leading zeros (zeros before non-zero digits) are not significant.
- Trailing zeros in a number containing a decimal point are significant.
Based on these rules:
- 0.0009 has one significant figure.
- 15,450.0 has six significant figures.
- 6x10³ has one significant figure.
- 87.990 has five significant figures.
- 30.42 has four significant figures.