A Set of Twins,Andrea and Courtney,are Initially 10 Years Old

question 30

Multiple Choice

A set of twins,Andrea and Courtney,are initially 10 years old.While Courtney remains on Earth,Andrea rides on a spaceship that travels away from Earth at a speed of 0.60c for 10 years (as measured by Courtney) .At the end of the trip,Courtney is 20 years old.How old is Andrea?

• A)10 years
• B)12 years
• C)18 years
• D)20 years