The phrase "a same ratio of" is not correct in English.
The correct form is "the same ratio of." You can use it when comparing proportions or relationships between quantities that are equal in ratio.
Example: "In this experiment, we used the same ratio of water to vinegar to ensure consistent results."
Alternatives: "an identical ratio of" or "the equivalent ratio of".
Even if we could find a way to increase the speed of our spacecraft a hundredfold — about the same ratio of speeds between a horse-drawn cart and a 747 jet plane — they would still take almost a thousand years to reach nearby stars, and as long to return.
BRET signals for assays in the presence of BRET-tagged Kras were calculated by subtracting the ratio of 'acceptor emission' over the 'donor emission' for a cell sample containing only the Rluc8 fusion protein from the same ratio of a second aliquot of cells containing both the Rluc8 and Venus fusion proteins.
The percentage of methylation of a certain gene was calculated as the ratio of amount of methylated gene/ACTB in a sample divided by the same ratio of SssI-treated sperm DNA and multiplied by 100 [ 18].
We designed a simulated eating task with the same ratio of rest and activity as was found on average in a video analysis of three meals consumed in a social environment.
[AlterNet, The Guardian] African-Americans and women are underrepresented among Occupy protesters nationwide, with African-Americans making up just 1.6 percent of the protest movement, and women taking up about a fifth of General Assemblies, roughly the same ratio of seats held by women in Congress.
All splits were performed in a stratified way to get the same ratio of patients with epilepsy.
A certain treatment that kills the same ratio of tumour cells in two different tumour types will give different results if the natural proliferation rates of tumour cells are different.
Ms. Angelou, an Arkansan too, recommends precisely the same ratio of corn bread to white bread as Ms. Deane -- three to one -- to ensure a light mixture.
The Braves, who have a solid division lead, have nevertheless created the same ratio of change in recent weeks.
This is about the same ratio of women who will develop an invasive breast cancer in their lifetime and the same ratio of men who will develop prostate cancer.
