Please solve the following problems

4. A real signal x(t) with the fundamental period T = 8 has the following nonzero Fourier series coefficients: Co = 1, C1 = c'1 = j, C3 = C23 = a) Plot the magnitude and phase spectra. b) Find the polar representation of the signal. c) Find the trigonometric representation of the signal.1. Which of the following is classified as investment in national income (GDP) accounting? A. building a new factory B. buying a 10-year-old house C. depositing money in a bank D. purchasing corporate stocks and bonds 2. The consumer price index in an economy is 180 one year and 189 the next year. The rate of inflation in the economy over that year period is: A. 1 percent. B. 5 percent. C. 8 percent. D. 18 percent. 3. In the short run, how will an increase in aggregate demand most likely affect the overall price level and real GDP? Price Level Real GDP A. Decrease Decrease B. Decrease Increase C. Increase Increase D. Increase Decrease 4. The limit of total productive capacity in an economy is set by: A. the amount of money in circulation. B. business demand for goods and services. C. the amount of government spending and taxation. D. the quantity and quality of its productive resources. 5. The basic money supply (MI) in the United States consists primarily of: A. currency and checkable deposits. B. currency and government bonds. C. currency, checkable deposits, and government bonds. D. currency, checkable deposits, and credit card accounts. 6. Which of the following actions by the Federal Reserve would have similar effects on the size of the U.S. money supply? A. decreasing the reserve ratio and selling government securities B. increasing the reserve ratio and selling government securities C. decreasing the discount rate and selling government securities D. increasing the discount rate and buying government securities