I am not aware of any Scripture that promises swifter or bigger answers if ten people pray for something instead of five or one hundred pray for something instead of ten. God can answer the prayers of one desperate mother praying alone in her room just as easily as he can answer the prayers of 10,000. Numbers by themselves do not impress the Lord. However, that doesn’t mean that united prayer is useless. United prayer halves our burdens and doubles our joys. And God is greatly glorified when his children come together to cry out to him in a time of great need. See Helping Through Prayer.