South Dakota is about 4.8 times smaller than Tanzania.

Tanzania is approximately 947,300 sq km, while South Dakota is approximately 196,540 sq km, making South Dakota 20.75% the size of Tanzania. Meanwhile, the population of Tanzania is ~63.9 million people (63.0 million fewer people live in South Dakota).
Tip: This to-scale comparison of Tanzania vs. South Dakota uses the Mercator projection, which distorts the size of regions near the poles.