Downloaded but not installed app I got gionee elife 7 mini
Just a day ago..
I put two games for downloading  (bad piggies and oil hunter)  and when the download was completed the  play store showed an error which stopped the installing process.  When the two game was not in my phone, I had 300mb of space . but now the phone showing only 50mb . how to free that space , please help  ... and my android is not rooted.
Some times happen that phones with short memory not permit to install many apps, in this case your phone has only 1 gb of RAM, but like 500 mb of this is occupied by the apps already present in the phone. To work good the phone need like 200 mb always available and for this motivation you can't install other apps despite you have 300mb of space. I got the same problem with my last phone, and apps like facebook occupied all the memory. It is only a problem of memory, but to be sure try to clear cache and data of Google Play following these steps:

1.Go to [Settings > Applications > Manage applications > Google app store]

2.Click [clear cache] and [clear data].

3.Open Google Play store and try to install the app again.

I hope I helped you, good luck!