IPA FE Subject A sample Question 26
A question IPA Japan published in 基本情報技術者試験 科目A サンプル問題 問26, translated into English. ITPEC is based on the same exams.
How many seconds are required to transfer 12 Mbytes of data by using a 1.5 Mbit/s transmission line? Here, the transmission efficiency of the line is 50%.
Explanation
128 seconds — convert the data to bits, then divide by the line speed actually available at 50% efficiency.
- •Data: 12 Mbytes × 8 = 96 Mbits
- •Effective speed: 1.5 Mbit/s × 0.5 = 0.75 Mbit/s
- •Time: 96 ÷ 0.75 = 128 seconds
Answer (d)
Why not others:
- •(a) 16 — divides bytes by bits per second (12 ÷ 0.75) without converting bytes to bits
- •(b) 32 — applies the 50% the wrong way: 96 ÷ 1.5 = 64 seconds, then halved instead of doubled, as if the efficiency made the line faster
- •(c) 64 — 96 ÷ 1.5, ignoring the 50% transmission efficiency
Key rule: Transfer time = data in bits ÷ (line speed × transmission efficiency); multiply bytes by 8 first.
Networks · AI-written, may contain errors
This question comes from the past questions IPA Japan publishes, translated into English by ITPEC Practice. ITPEC Practice is an independent study tool and is not affiliated with IPA or ITPEC. See the original paper (PDF) or Report an issue.