Chapter 3, Problem 29E

(a)

To determine

To find: the percent of days it actually rain.

Answer to Problem 29E

9.3%

Explanation of Solution

Given:

	Rain	No rain
Rain	27	63
No rain	7	268

Calculation:

Total number of days rained is 34. Total number of days is 365.

Therefore, the percent of day it actually rain is

  $\begin{array}{c}\frac{\text{Number}\text{of}\text{rain}\text{days}}{\text{Total number}\text{of}\text{days}}=\frac{34}{365}\times 100\\ =9.3\%\end{array}$

Therefore, the percent of actually rained days is 9.3%.

(b)

To determine

To find: the percent of days was rain predicted.

Answer to Problem 29E

24.7%

Explanation of Solution

Given:

	Rain	No rain
Rain	27	63
No rain	7	268

Calculation:

Total numbers of days were rain predicted is 90.

And total number of days is 365.

Therefore, the percent of days was rain predicted is

  $\begin{array}{c}\frac{\text{Number rain predicted}\text{days}}{\text{Total number}\text{of}\text{days}}=\frac{90}{365}\times 100\\ =24.7\%\end{array}$

Therefore, the percent of rain predicted days is 24.7%

(c)

To determine

To find: the percent of the time was the forecast correct.

Answer to Problem 29E

80.8%

Explanation of Solution

Given:

	Rain	No rain
Rain	27	63
No rain	7	268

Calculation:

The rain forecast is correct = 27 times and

No rain forecast is correct =268 times.

Total correct forecast is 27+268=295.

Total number of days is 365.

Therefore, the percent of the time was the forecast correct is

  $\begin{array}{c}\frac{\text{Number of correct forecasts}}{\text{Total number}\text{of}\text{days}}=\frac{295}{365}\times 100\\ =80.8\%\end{array}$

Therefore, the required percent correct forecast is 80.8%.

(d)

To determine

To Explain: the about the accurate prediction of the weather forecast and briefly explanation with appropriate graph.

Explanation of Solution

Given:

	Rain	No rain
Rain	27	63
No rain	7	268

Graph:

  

  $\frac{27}{34}\times 100\%=79.4\%$ Actually rain and forecast also predicts the as it is an $\frac{7}{34}\times 100\%=20.6\%$ actually not rain and forecast predicts the rain. There are $\frac{268}{331}\times 100\%=81.0\%$ actually not rain and forecast also predicts the as it is and $\frac{63}{331}\times 100\%=19.0\%$ actually rain and forecast predicts no rain.