These group of people have contributed to the success.

English as a Second Language English Vocabulary, Grammar and Idioms
1
  1. These group of investors have brought significant development into the country.
  2. The vast development of the city were brought in by foreign investor.
  3. These group of people have contributed to the success of this country’s economy.

Are the above sentences correct? Please advise.

2
  1. This group of investors has brought significant development into the country. (or ‘These investors have brought…’)
  2. The vast development of the city were brought in by foreign investor. <-- ‘brought’ does not really work well here. I suggest
    The vast development of the city was made possible by foreign investors.
  3. These group of people have contributed to the success of this country’s economy. <-- As (1) this should be ‘This group of people has…’