Friday

December 19, 2014

December 19, 2014

Posted by **A Canadian** on Wednesday, January 23, 2013 at 11:20pm.

The answer is 9 weeks.

This is what I did, and it's clearly wrong:

tn = 7 + (n-1)13

tn = 7 + 13n - 13

tn = 13n - 6

100 = 13n - 6

100 + 6 = 13n

106/13 = n

I get a crazy decimal (8.1538....) which shouldn't be the answer...

What am I doing wrong, and how do you properly answer this question?

Thanks very much in advance!

- Math -
**Reiny**, Thursday, January 24, 2013 at 8:37amYou did just fine

it said "more than 100 mm"

so

13n - 6 > 100

13n >106

n > 106/13 or > 8.15..

So you would answer...

" the plant would be more than 100 mm in the 9th week"

check:

week 8 = t8 = a+7d = 7+7(13) = 98 , less than 100

week 9 = t9 = a+8d = 7+8(13) = 111 , more than 100

**Answer this Question**

**Related Questions**

Math - The height of a plant after each of the first three weeks was 7mm, 20mm, ...

Math - The height of a plant after each of the first three weeks was 7mm, 20mm...

math - a student plants a seed, after the speed sprouts the student monitors the...

6grade math - When Marcia started walking a 6 mile section of a trail it took 3....

6grade math - When Marcia started walking a 6 mile section of the trail , it ...

Math - When Marcia started walking a 6 mile section of the trail, it took her 3....

math - I have a table with this info. plant growth: Week 1 - 1 inch, week2 -4 ...

Algebra - 7. Johnny needs to save $24.00 to buy a new video game. Three weeks ...

math - Over the past two weeks, Jane earned $292 and $193 respectively, at her ...

math - Over the past two weeks, Jane earned $292 and $193 respectively, at her ...