Joseph and his family were going to the beach. Joseph's sister was running late so Joseph left their house with his mom. Joseph's dad waited for Joseph's sister to get ready and left one hour later driving 75 km/hour in an effort to catch up to Joseph and Joseph's mom. After driving for four hours Joseph's dad finally caught up. How fast was Joseph's mom driving?

Question

Mathematics

Keira Pugh

12 October, 10:03

Joseph and his family were going to the beach. Joseph's sister was running late so Joseph left their house with his mom. Joseph's dad waited for Joseph's sister to get ready and left one hour later driving 75 km/hour in an effort to catch up to Joseph and Joseph's mom. After driving for four hours Joseph's dad finally caught up. How fast was Joseph's mom driving?

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Answers (1)

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Judith Leonard · Answer 1

60 km/hr.

Step-by-step explanation:

When Dad caught up the the time he had been driving was 4 hours and the time Mom had been driving was 1 + 4 = 5 hours.

They both drove the same distance, d km.

For Dad:

speed = d / time

75 = d / 4

d = 75 * 4 = 300 km.

Mom took 5 hours to travel this distance, so

Mom's speed was 300 / 5 = 60 km/hr.