Please help on 2, 3, and 4.

2. $350

3a: 15 is half of 30, so knowing that means the answer is 50%

3b. 3 is 1/4 of 12 because 3x4 is 12, meaning that 3 is 25% of 12.

3c. 6 over 10 as a decimal is 0.6. Which as a percent is 60%

4. Noah's method does work because 20% x 5 is equal to 100% of a number.

step-by-step explanation: a reaction is first order. if the initial reactant concentration is 0.0200 m, and 25.0 days later the concentration is 6.25 x 10-4 m, then its half-life is:

an advantage of the standard deviation is that it increases as the dispersion of the data increases. e. the interquartile range is preferred when the data are not skewed or no have outliers. an advantage of the standard deviation is that it uses all the observations in its computation.