Answer:
According to the image, the approximate QT interval is 0.4 seconds.
Step-by-step explanation:
The QT interval is the space between the beginning of the QRS complex and the end of the T wave, which represents from the beginning of depolarization to ventricular repolarization.
Considering that the extandardized measurements of an EKG, where the paper circulates at a speed of 25 mm/s, 1 mm horizontal —measuring time— has an equivalence of 0.04 s.
In the image, there is 10 mm between the beginning of the QRS and the end of the T wave, so:
0.04 seconds X 10 mm = 0.4 seconds.
Then, the estimated QT interval is 0.4 seconds.