4. The U.S. Bureau of Labor Statistics (BLS) conducts bi-monthly household surveys to measure labor force status in the United States. The survey provides a measure of employed people, such as nonfarm employment, hours, and earnings by industry. Data collected from this survey will be used to report and estimate employment levels and trends in the US.

(1) The table as following provides us the employment situations in April 2020 (04/2020) and November 2021 (11/2021) in the US. With the information given about adult population (Adult 16+), labor force (L), employed (E), calculate the values of unemployed (U), unemployment rate (UR) and labor force participation rate (LFPR) in the two periods. Also, use the data of 11/2021 to show step-by-step solutions for U, UR, LFPR in that month.

Variable	Definition	04/2020 (number, thousand)	11/2021 (number, thousand)
Adult 16+	Population 16 above (number)	259,896	261,085
L	Labor force (number)	156,481	160,536
E	Employed (number)	133,403	149,809
U	Unemployed (number)
UR	Unemployment rate %
LFPR	Labor Force Participation Rate %

(2) The natural rate of unemployment is a hypothetical (not directly observable) unemployment rate which is consistent with stable inflation, aggregate demand and production in long-run level. Suppose economists have found current job separation rate (s) and job finding rate (f) in the US are 4% and 85%. Then what is the current natural rate of unemployment of the US? How much will be natural rate of unemployment if job finding rate goes up to 90%? What if job separation rate goes down to 3%?