Tanzania is about 4.8 times bigger than South Dakota.

South Dakota is approximately 196,540 sq km, while Tanzania is approximately 947,300 sq km, making Tanzania 382% larger than South Dakota. Meanwhile, the population of South Dakota is ~814,180 people (63.0 million more people live in Tanzania).
Tip: This to-scale comparison of South Dakota vs. Tanzania uses the Mercator projection, which distorts the size of regions near the poles.