The phrase "tell with certainty" is correct and usable in written English.
You could use it when you want to express that someone is sure or confident about something. For example: "He was able to tell with certainty who had been causing the disturbance."
How can you tell with certainty which switch controls the light bulb?
There is no way fans can tell with certainty that their hometown heroes have not been on the juice.
No one in Nigeria can tell with certainty how many policemen, soldiers or civil servants there are today in service".
During a visit to the site on Sunday, there was no way to tell with certainty whether it contained human remains.
At this point, no one can tell with certainty what, if any, changes his successor, Arthur F. Burns, the econo mist, will bring to the na tion's central bank.
No one in Nigeria can tell with certainty how many policemen, soldiers or civil servants there are today in service". Making more data more freely available can create citizens who are more aware.
"Are we, in those instances at least, willing to say this person whose individual risk cannot be told with certainty is a member of a group of people that, as a group, are reliably at higher risk than other people?" he said.
It is too early to tell with any certainty why the flood projections in south Louisiana have diverged with reality, officials said.
Langleben, who advises No Lie MRI, says he is now able to tell with 88% certainty whether individuals are lying (see Nature 437, 457; 2005).
In the Pentagon in 1965, again by applying metrics targets hit, captives taken, weapons seized, the enemy's body-count he could tell with equal certainty that America was losing.The South Vietnamese, America's allies, were cavalier with numbody-count he
Tests using DNA to determine a fetus's sex were shown to be remarkably accurate, able to tell with 95 percent certainty as early as seven weeks into pregnancy, if a woman is carrying a boy or girl.
