Answer:
21
Step-by-step explanation:
3n - 15 - 6 + 2n = 4n
3 n + 2n = 4n + 15 + 6
5 n - 4n = 15 + 6
n = 21
Area of circle = πr²
Area of circle = π(4÷2)² = 12.57 cm²
Answer:
25.92 feet
Step-by-step explanation:
In the first minute, the hot air balloon rises 120 feet.
And it is given that, the balloon rises in a minute only 60% of the height it rose in the previous minute.
Therefore, in the second minute, the balloon rises by (120×0.6) =72 feet
And in the third minute, the balloon rises by (72×0.6) =43.2 feet
Hence, in the fourth minute, the balloon rises by (43.2 ×0.6) =25.92 feet (Answer)
Answer: true
Step-by-step explanation:
Z-tests are statistical calculations that can be used to compare the population mean to a sample mean The z-score is used to tellsbhow far in standard deviations a data point is from the mean of the data set. z-test compares a sample to a defined population and is typically used for dealing with problems relating to large samples (n > 30). Z-tests can also be used to test a hypothesis. Z-test is most useful when the standard deviation is known.
Like z-tests, t-tests are used to test a hypothesis, but a t-test asks whether a difference between the means of two groups is not likely to have occurred because of random chance. Usually, t-tests are used when dealing with problems with a small sample size (n < 30).
Both tests (z-tests and t-tests) are used in data with normal distribution (a sample data or population data that is evenly distributed around the mean).
