英検準1級のincrease by・increase to・twiceを実戦40問で比較｜割合の増減・倍数【全解答】

英検準1級の長文で「20％から30％になった」「20％増えた」「20パーセントポイント増えた」を混同すると、内容一致で数量を取り違えます。慶英会では、割合・倍数・比較・下限・概数を独自40問（英文解釈12、4択12、要約訂正8、4長文8）と全和訳・正解根拠で学習できる教材を公開します。

英検準1級の公式形式は、短文語句空所補充18問・長文空所補充6問・長文内容一致7問です（英検協会公式）。本教材は独自の英文を使った読解練習であり、実際の試験に数値計算の独立大問があるという意味ではありません。架空の調査・統計を使っています。

結論｜数値表現の5つの区別

• from 20% to 30%：差は10パーセントポイント。元の20％からの相対的増加率は50％。
• increased by 20%：増加前の値の20％だけ増えた。100人なら120人。
• increased to 20%：変化後の数値が20％。元の数値が分からなければ増加幅は不明。
• twice as many：元の人数の2倍。「200％増」ではなく、増加分は元の100％。
• at least／at most／fewer than／nearly：下限・上限・未満・概数を示す。exactlyやallと取り違えない。

演習A｜数値英文を正確に和訳する12問

1. A1. The share of students using the library rose from 20% to 30%.
2. A2. The number of visitors increased by 20%.
3. A3. The percentage of residents supporting the plan increased to 40%.
4. A4. The new bus route carried twice as many passengers as the old route.
5. A5. Fewer than half of the participants completed the survey.
6. A6. At least a quarter of the families lacked reliable internet access.
7. A7. Nearly all the respondents agreed, but the sample was small.
8. A8. The rate fell by ten percentage points, from 55% to 45%.
9. A9. Compared with last year, attendance was 15% higher.
10. A10. The rate was three times that recorded in the neighboring district.
11. A11. The total rose by nearly a third during the trial.
12. A12. Only two of the eight routes showed improvement.

演習B｜英文と一致する4択12問

正しい説明を一つ選びます。数値の「差」「増加率」「母数」「限定」のどれを問われているか判断してください。

13. B1. A survey’s approval rate rose from 40% to 50%.
    1. An increase of 10 percentage points
    2. A fall of 10 percentage points
    3. A rise to 10%
    4. Exactly 10 additional supporters
14. B2. The number of users rose from 100 to 120.
    1. The increase was 20 percentage points
    2. The number increased by 20%
    3. The total fell by 20%
    4. The new total was 20
15. B3. The share increased to 25%.
    1. It increased by 25 percentage points
    2. It began at 25%
    3. Its final reported value was 25%
    4. Every participant supported the plan
16. B4. The figure increased by 25%.
    1. Its final value was exactly 25%
    2. It declined to 25%
    3. It rose by 25 percentage points
    4. Its new value was 1.25 times its earlier value
17. B5. Fewer than one in five respondents selected the first option.
    1. Less than 20% selected it
    2. Exactly 20% selected it
    3. Exactly five respondents selected it
    4. All respondents selected it
18. B6. At most 30% of the budget was allocated to repairs.
    1. At least 30% was allocated
    2. No more than 30% was allocated
    3. Exactly 30% was allocated
    4. All funds were used for repairs
19. B7. The new machine produced half as much waste as the old one.
    1. It produced twice the waste
    2. It produced no waste
    3. It produced 50% of the old machine’s waste
    4. It reduced the waste rate by 50 percentage points
20. B8. There were twice as many applicants as last year.
    1. The applicant count increased by 200%
    2. The approval rate doubled
    3. Applicant numbers were unchanged
    4. The applicant count doubled
21. B9. The rate fell from 80% to 60%.
    1. It declined by 20 percentage points
    2. It declined by 20% relative to the old rate
    3. It declined to 20%
    4. It became one third of the earlier rate
22. B10. Roughly two thirds of volunteers attended.
    1. Every resident attended
    2. About 67% of volunteers attended
    3. Exactly 20 volunteers attended
    4. No volunteers attended
23. B11. Only three of twelve districts reported a decline.
    1. All districts declined
    2. Three quarters of districts declined
    3. One quarter of districts reported a decline
    4. One quarter of residents moved away
24. B12. The report stated that the figure had probably risen.
    1. An increase was proved beyond doubt
    2. Every district showed an increase
    3. The figure certainly fell
    4. A rise was considered likely but not proved

演習C｜数値の意味を変えた要約を直す8問

25. C1 原文：The rate rose from 30% to 45%. 誤要約：It rose by 15%.
26. C2 原文：Attendance increased by 25%. 誤要約：Attendance increased to 25%.
27. C3 原文：The rate increased to 60%. 誤要約：The rate increased by 60%.
28. C4 原文：Only four of ten classes participated. 誤要約：All classes participated.
29. C5 原文：The service had twice as many users. 誤要約：It had three times as many users.
30. C6 原文：Fewer than 20% completed the survey. 誤要約：Exactly 20% completed it.
31. C7 原文：The share fell by five percentage points. 誤要約：It fell by exactly 5% relative to its old value.
32. C8 原文：Researchers reported a possible increase. 誤要約：They proved an increase.

演習D｜独自4長文・内容一致8問

長文1｜図書館の利用率

A fictional school found that the share of students using its library at lunchtime had risen from 20% to 30% after a timetable change. The number of students enrolled at the school had also changed, so the librarians warned against assuming that exactly ten additional students had attended. They noted that changes in other school activities could have contributed. More evidence was needed before the timetable could be credited with the result.

D1. How did the share of users change?

1. It fell by ten points
2. It rose by ten percentage points
3. It rose to ten percent
4. It doubled

D2. Why couldn’t the number of additional users be inferred directly?

1. The library had closed
2. No percentages were recorded
3. Enrollment numbers had also changed
4. Every student used the library

長文2｜地域バスの乗客数

A town reported that a revised bus route carried twice as many passengers as a comparable older route during one weekend. Officials welcomed the observation but noted that the two routes served different neighborhoods. The weekend also coincided with a local festival, and typical weekday demand had not been measured. The director said the result justified further study, not a guarantee of long-term superiority.

D3. What does twice as many passengers mean?

1. Two times the comparison route’s passenger count
2. Two extra passengers
3. Three times the count
4. Twice the approval rate

D4. Why were officials cautious?

1. All buses were empty
2. No routes were compared
3. Both routes had the same conditions
4. Neighborhoods and a festival could influence the comparison

長文3｜アンケートの回答者

In a fictional town, nearly all respondents supported adding weekend workshops. However, the survey link had been shared mainly with people who already used the center. The report therefore said that approval among respondents was high, but it did not necessarily reflect the views of all residents. Officials planned another survey with wider participation.

D5. Which statement matches the results?

1. Every resident supported the idea
2. No respondent supported it
3. Nearly all respondents supported it, not necessarily all residents
4. Only employees were surveyed

D6. What did officials plan?

1. A wider survey
2. Immediate permanent approval
3. Closing the center
4. Canceling all workshops

長文4｜医療機関の予約

A fictional clinic reported that the share of appointments starting on time had risen from 70% to 80% after it introduced a new booking system. Staff pointed out that this was a rise of ten percentage points, not evidence that waiting times had fallen by ten minutes. The clinic also hired additional reception staff during the trial. Managers planned further comparisons before determining how much of the change could be attributed to the software.

D7. How did the on-time share change?

1. By ten minutes
2. To ten percent
3. By ten passengers
4. By ten percentage points

D8. Why was the software’s impact uncertain?

1. The clinic had no patients
2. Additional reception staff were hired
3. Every appointment began late
4. There was no booking system

全40問の正解・和訳・詳しい解説

A｜英文解釈12問

1. A1：図書館利用の割合は20％から30％へ上がった。10パーセントポイント増で、相対的には50％増。
2. A2：来訪者数は20％増えた。by 20%は以前の人数に対する20％増。
3. A3：計画への賛成率は40％まで増えた。to 40%は到達した割合で、変化幅は不明。
4. A4：新路線の乗客数は旧路線の2倍だった。twice as manyは元の2倍。
5. A5：参加者の半数未満しか調査を完了しなかった。fewer than halfは50％未満。
6. A6：少なくとも4分の1の家庭が安定したネット回線を利用できなかった。at leastは下限。
7. A7：ほとんどの回答者が賛成したが標本は少なかった。nearly allはallではない。
8. A8：割合は55％から45％へ10パーセントポイント下がった。相対減少率10％という意味ではない。
9. A9：前年に比べ出席者数は15％多かった。比較の基準は前年。
10. A10：その率は隣の地区の3倍だった。比較したのは人数でなくrate。
11. A11：試行中に総量は約3分の1増えた。新しい総量が3分の1という意味ではない。
12. A12：8路線のうち2路線だけが改善した。人数の25％が改善したとは言えない。

B｜4択12問

13. B1 正解A：50−40＝10パーセントポイント。何人増えたかは不明。
14. B2 正解B：100→120、差20は元の100の20％。
15. B3 正解C：to 25%は最終値25％。初期値は与えられていない。
16. B4 正解D：by 25%なら以前の1.25倍の値になる。
17. B5 正解A：one in fiveは20％。fewer thanは20％未満。
18. B6 正解B：at most 30%は30％以下。ちょうど30％とは確定しない。
19. B7 正解C：half as muchは量が以前の50％。
20. B8 正解D：twice as manyは2倍。200％増とは異なる。
21. B9 正解A：80％→60％は20ポイント減。元の80％に対しては25％の相対減少。
22. B10 正解B：roughly two thirdsは約66.7％。回答対象はボランティア。
23. B11 正解C：12地区のうち3地区であり、3÷12＝25％。
24. B12 正解D：probablyは確率の高い見通し。確証はない。

C｜誤った要約の訂正8問

25. C1：The rate rose by 15 percentage points, from 30% to 45%. 15ポイント増で、相対増加率は50％。
26. C2：Attendance increased by 25%. 増加幅を到達値に変えない。
27. C3：The rate increased to 60%. 増加前の数が不明なので相対増加率60％とは断定できない。
28. C4：Only four of the ten classes participated. 10クラスのうち4クラスのみ。
29. C5：The service had twice as many users. 2倍と3倍を混同しない。
30. C6：Fewer than 20% completed the survey. 20％未満は20％ちょうどではない。
31. C7：The share fell by five percentage points. 割合のポイント差と元の値からの相対減少率は別。
32. C8：Researchers reported a possible increase. 観測された可能性を証明済みと表現しない。

D｜4長文8問の正解と本文根拠

33. D1 正解B：from 20% to 30%が根拠。10パーセントポイント増。
34. D2 正解C：The number of students enrolled … had also changedが根拠。母数が変わっていた。
35. D3 正解A：twice as many passengersが根拠。人数が2倍。
36. D4 正解D：different neighborhoods／coincided with a local festivalが比較上の制約。
37. D5 正解C：nearly all respondents／not necessarily … all residentsが根拠。回答者と全住民は異なる。
38. D6 正解A：planned another survey with wider participation。
39. D7 正解D：from 70% to 80%とten percentage pointsが根拠。
40. D8 正解B：also hired additional reception staffが根拠。ソフトの効果とは限らない。

7日間の復習方法

1. 1日目：A12問を和訳し基準の値を確認
2. 2日目：B12問の解答と増減の理由を確認
3. 3日目：C8問を正確な英文に書き直す
4. 4日目：D4長文8問の根拠を探す
5. 5日目：increase byとincrease toの自作文を作成
6. 6日目：数字の情報を変えずに60〜70語で要約する
7. 7日目：公式過去問で初見の数値・数量表現を読む

よくある質問

20％から30％になったら10％増ですか？

10パーセントポイント増です。元の20％に対する相対増加率は50％です。「10％増」と書くと意味が変わるため注意してください。

twice as manyは200％増ですか？

いいえ。2倍は元の200％の量で、相対的な増加分は100％です。200％増なら元の3倍です。

at least 25%はちょうど25%ですか？

いいえ。25％以上という下限を表しています。

本記事の40問で英検準1級のCSEを計算できますか？

できません。独自の長文・数量表現練習であり、公式問題数・採点方式とは異なります。

次に取り組む慶英会の無料教材

only・almost・at leastの限定40問／統計・報道の長文15問／要約で意味を変えない32問。

慶英会では、英検準1級の長文を数値・比較・限定表現まで正確に読めるよう個別に学習を支援しています。最大1か月完全無料体験・学習相談はこちら。

参考にした主な公式情報

日本英語検定協会｜準1級試験内容／日本英語検定協会｜公式過去問。2026年10月28日確認。数値の事例・全40問・解答は慶英会の独自制作で、実在の調査結果ではありません。