Big Mac Prices and (spot) nominal exchange rates with respect to the US dollar and GDP per capita in USD are presented in the table below for few countries (source: The Economist). We focus on Purchasing Power Parity (PPP) based on Big Mac prices.

Country	Big Mac Price in local currency	Spot nominal exchange rate (mid-quotes) with respect to the USD (Foreign currency units/USD)
USA	3.2 USD	-
Switzerland	6.30 CHF	1.25
Russia	50 RUB	25
Taiwan	75 TWD	33
Thailand	62 THB	34.7

Which answer(s) are correct?

a. According to PPP, the Swiss Franc is undervalued with respect to the US dollar

b. PPP would be verified if a Big Mac in Taiwan would cost approximately 106 Taiwan Dollars.

c. The exchange rate implied by PPP for Russia is close to 15 RUB/USD.

d. According to PPP, the Russian ruble is overvalued by roughly 40% with respect to the US dollar