1. Find one number that when rounded to the nearest ten is 5700.
2. On August 23, 1989, it was estimated that 1,500,000 people joined hands in a human chain stretching 370 miles to protest the fiftieth anniversary of the pact that allowed what was then the Soviet Union to annex the Baltic nations in 1939. If the estimate of the number of people is to the nearest hundred thousand, determine the largest possible number of people in the chain.
3. Estimate the perimeter of the triangle by first rounding the length of each side to the nearest hundred.