NEW TREASURE Stage3の確率・予測32問｜likely・unlikely・降水確率と英語の資料読解【全解説】

[1] A school planning a fictional museum visit checked a weather forecast for the area around the museum. The forecast showed a forty-percent chance of measurable precipitation during the afternoon. It also predicted a temperature of twenty-four degrees Celsius. The students had originally hoped to hold an outdoor discussion after the visit, so they wanted to understand the numbers carefully.

[2] One student said that forty percent meant rain would fall for exactly forty percent of the afternoon. Another thought it meant exactly forty percent of the city would be covered by rain. Their teacher explained that a precipitation probability for a location and specified period should not be read as either of those claims. It expresses an estimated chance of precipitation at the forecast location during that period.

[3] The team did not conclude that rain was guaranteed or impossible. It chose a plan with a covered alternative discussion area. The students also checked whether the forecast had been updated and promised to follow official safety notices if weather conditions changed. In their final announcement, they wrote about the probability accurately rather than claiming to know how many minutes it would rain.

1. Q1. 午後の降水確率は何％か。

   解答・計算と不確実性の根拠

   解答：40%.

   根拠：架空の予報の数値。

2. Q2. 予想気温は何度か。

   解答・計算と不確実性の根拠

   解答：24°C.

   根拠：降水確率とは別の予測項目。

3. Q3. 雨が午後の40％の時間だけ降るという意味か。

   解答・計算と不確実性の根拠

   解答：No.

   根拠：確率は時間割合ではない。

4. Q4. 市域の40％に必ず雨が降る意味か。

   解答・計算と不確実性の根拠

   解答：No.

   根拠：降水範囲の確定面積ではない。

5. Q5. 40％だから雨が必ず降るか。

   解答・計算と不確実性の根拠

   解答：No.

   根拠：確率は確定事実ではない。

6. Q6. 40％だから雨は降らないと断定できるか。

   解答・計算と不確実性の根拠

   解答：No.

   根拠：起こる可能性がある。

7. Q7. 計画に加えた対応は何か。

   解答・計算と不確実性の根拠

   解答：A covered alternative discussion area.

   根拠：不確実性に備えた代替案。

8. Q8. 英語35〜50語で最新予報と準備をまとめる。

   解答・計算と不確実性の根拠

   解答：The fictional forecast gives a 40 percent chance of measurable precipitation in the afternoon and a temperature of 24 degrees. This does not mean rain for 40 percent of the time. The class prepared a covered alternative and planned to check updated official information.

   根拠：確率・時間割合の誤解・行動を示す。

[1] An English class created a simple game using five identical cards. Three were marked red and two were marked blue. All cards were placed in an opaque bag, mixed, and drawn without looking. Every individual card was equally likely to be selected. The class first considered the probability of drawing one red card.

[2] The probability of red was three out of five, or sixty percent. The probability of blue was two out of five, or forty percent. When the teacher put the card back into the bag before drawing again, the second draw had the same probabilities as the first. If the card was not replaced, however, the contents of the bag changed, and the next probability depended on the first result.

[3] The students compared these conditions. With replacement, two red draws have probability three-fifths times three-fifths, or nine twenty-fifths. Without replacement, if the first card is red, only two red cards remain among four cards, so the chance of red on the second draw is two-fourths. The teacher emphasized that a probability calculation describes a model. It does not guarantee a particular result in only one or two actual draws.

9. Q9. 袋の赤と青のカードは何枚ずつか。

   解答・計算と不確実性の根拠

   解答：Three red and two blue.

   根拠：全5枚。

10. Q10. 最初に赤を引く確率は。

    解答・計算と不確実性の根拠

    解答：3/5 = 60%.

    根拠：赤3/全体5。

11. Q11. 最初に青を引く確率は。

    解答・計算と不確実性の根拠

    解答：2/5 = 40%.

    根拠：青2/全体5。

12. Q12. 復元抽出（戻す）で2回連続赤の確率は。

    解答・計算と不確実性の根拠

    解答：9/25 = 36%.

    根拠：3/5 × 3/5。

13. Q13. 赤を1枚引いて戻さない場合、2枚目も赤の条件付き確率は。

    解答・計算と不確実性の根拠

    解答：2/4 = 50%.

    根拠：残り赤2/全体4。

14. Q14. 戻さない場合、順に赤・赤となる確率は。

    解答・計算と不確実性の根拠

    解答：3/10 = 30%.

    根拠：3/5 × 2/4。

15. Q15. 赤の確率60％なら一回目は必ず赤か。

    解答・計算と不確実性の根拠

    解答：No.

    根拠：確率と確実性を区別。

16. Q16. 英語35〜50語で復元抽出の重要性を説明する。

    解答・計算と不確実性の根拠

    解答：The bag contains three red cards and two blue cards. With replacement, a second draw has the same probabilities as the first, and two red draws have probability 9/25. Without replacement, a first red draw changes the remaining numbers, so the next probability becomes 2/4.

    根拠：条件の違いと計算根拠。

[1] A fictional student council asked eighty participants which information format they preferred. Forty-eight chose printed notices, and thirty-two chose digital notices. Each person selected one option. The group correctly calculated that sixty percent of the respondents preferred printed notices.

[2] A student then announced that the next student to enter the school had exactly a sixty-percent chance of preferring paper. The teacher asked whether the eighty respondents were a randomly selected and representative sample of the whole school. The group did not know. The figures described the responses they had collected, but they were not enough on their own to assign a reliable probability to an unknown future student.

[3] The council wrote a more careful report. It said, ‘In our survey, 48 out of 80 respondents selected printed notices.’ It did not promise that the same share would apply to every class, grade, or new participant. Before changing school communication, it suggested asking a wider range of students and checking practical access needs.

17. Q17. 回答者は何人か。

    解答・計算と不確実性の根拠

    解答：Eighty.

    根拠：分母80人。

18. Q18. 紙を選んだのは何人か。

    解答・計算と不確実性の根拠

    解答：Forty-eight.

    根拠：48人。

19. Q19. デジタルを選んだのは何人か。

    解答・計算と不確実性の根拠

    解答：Thirty-two.

    根拠：32人。

20. Q20. 紙を選んだ割合は。

    解答・計算と不確実性の根拠

    解答：60%.

    根拠：48/80×100。

21. Q21. デジタルを選んだ割合は。

    解答・計算と不確実性の根拠

    解答：40%.

    根拠：32/80×100。

22. Q22. 次に来る誰かが必ず60％の確率で紙を選ぶと言えるか。

    解答・計算と不確実性の根拠

    解答：No.

    根拠：標本代表性などが不明。

23. Q23. 報告書の慎重な表現は。

    解答・計算と不確実性の根拠

    解答：48 out of 80 respondents selected printed notices.

    根拠：対象を今回の回答者に限定。

24. Q24. 英語35〜50語で結果と限界を書く。

    解答・計算と不確実性の根拠

    解答：In an imaginary survey, 48 of 80 students preferred printed notices and 32 preferred digital ones. That is 60 percent and 40 percent of the respondents. The survey does not prove that the same proportions apply across the whole school, so a wider sample may be useful.

    根拠：回答者割合と一般化を区別。

[1] In a fictional science activity, students tested whether a simple paper route guide helped someone reach a room without asking for directions. Five volunteer readers used the new guide, and three reached the room without needing help. Two asked the teacher for clarification. The class called this an observed success proportion of three out of five, or sixty percent.

[2] One student said the next visitor would definitely have a sixty-percent probability of succeeding. Another pointed out that the trial involved only five participants, who may have been more familiar with the building than other visitors. The team had not recorded how long anyone took or compared the guide fairly with an earlier version. These limits made the figure unsuitable as a guaranteed probability for any future reader.

[3] The students planned to test more visitors, define what success meant, and check the same outcome under clear conditions. Their teacher explained that five observations were useful as a starting point, but not enough to prove a universal success rate. The responsible report stated the observed results first, followed by what remained uncertain.

25. Q25. 試行に参加した人数は。

    解答・計算と不確実性の根拠

    解答：Five.

    根拠：架空の5人。

26. Q26. 自力で部屋に着いた人数は。

    解答・計算と不確実性の根拠

    解答：Three.

    根拠：3人。

27. Q27. 助けを求めた人数は。

    解答・計算と不確実性の根拠

    解答：Two.

    根拠：5−3。

28. Q28. 観察された成功割合は。

    解答・計算と不確実性の根拠

    解答：60%.

    根拠：3/5×100。

29. Q29. 次の人が成功する確率を正確に60％と言えるか。

    解答・計算と不確実性の根拠

    解答：No.

    根拠：少数の観察から未来の個人確率は確定できない。

30. Q30. 比較のため不足している資料を一つ。

    解答・計算と不確実性の根拠

    解答：A fair test of the earlier guide, or route-finding time.

    根拠：公平な比較や時間の記録。

31. Q31. より信頼できる報告のための改善は。

    解答・計算と不確実性の根拠

    解答：Include more visitors and define success consistently.

    根拠：標本・測定条件の改善。

32. Q32. 英語35〜50語で観察と不確実性を説明する。

    解答・計算と不確実性の根拠

    解答：Three of five volunteers found the room without help, an observed rate of 60 percent. However, the group was small and may not represent future visitors. The team should test more people and compare conditions before making a broad claim about the guide’s success.

    根拠：結果・標本・条件の限界。