Question
peter took a 1,500 mile trip in 5 days. each day, he drove 30 miles more than the day before. how many miles did he cover on the first day?
Answers
Reiny
You have an arithmetic series,
where d = 30 , and Sum(5) = 1500 , a is first term
sum(n) = (n/2)(2a + (n-1)d)
1500 = (5/2)(2a + 120)
600 = 2a+120
2a=480
a = 240
On the first day he went 240 miles
check: 240 + 270 + 300 + 330 + 360 = 1500
where d = 30 , and Sum(5) = 1500 , a is first term
sum(n) = (n/2)(2a + (n-1)d)
1500 = (5/2)(2a + 120)
600 = 2a+120
2a=480
a = 240
On the first day he went 240 miles
check: 240 + 270 + 300 + 330 + 360 = 1500