change the seed of spectrum plot and change confusing start of sentence

Closes #209
6 jobs for fix_209 in 9 minutes and 8 seconds (queued for 1 second)
Status Name Job ID Coverage
  Execute
passed execute_ipynbs #25549

00:06:37

passed mirror to github #25550

00:00:32

 
  Build
passed edx archive #25551

00:01:04

passed ocw website #25553

00:01:02

passed pelican website #25552

00:01:41

 
  Deploy
passed upload test website #25554

00:00:49