density=mass/volume and the volume of a sphere is (4πr^3)/3 so
2=8.4(3)/(4πr^3)
8πr^3=25.2
r^3=25.2/(8π)
r^3=3.15/π
r=(3.15/π)^(1/3) cm
r≈1.00089
r≈1 cm
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