A sample of radium has a weight of 1.5 mg and a half-life of approximately 6 years. How much of the sample will remain after 1 year?

Areflection of shape i across the y-axis, followed by a , and then a translation left 6 units and down 4 units confirms congruence between shape i and shape ii. alternatively, a of shape ii about the origin, followed by a reflection across the y-axis, and then a translation right 4 units and up 6 units confirms congruence between shape ii and shape i.