Q1. How many students chose "print only"?

1. ANone
2. B16
3. C32
4. D84

no student chose "print only" とあるので A。

Q2. What happened when "print only" was removed?

1. AMore students chose the expensive plan.
2. BNobody chose any plan.
3. CFewer students chose the most expensive plan.
4. DThe price went down.

84人から32人に減ったので C。

Q3. In this passage, a "good deal" is ...

1. Aa very difficult plan
2. Bsomething that seems worth the money
3. Ca kind of magazine
4. Da plan that nobody wants

a good deal は「お得な買い物・取引」。お金に見合う価値があるように見えるものなので B。

Q1. Why did the print-only option work as a decoy?

1. AIt was the cheapest plan.
2. BIt made the combined plan look like a bargain.
3. CIt was the most popular plan.
4. DIt was only available online.

making the combined plan look like a bargain とあるので B。

Q2. According to the passage, why do people fall for decoys?

1. AThey always choose the cheapest option.
2. BThey read every detail carefully.
3. CThey do not like magazines.
4. DThey find it hard to judge absolute value and compare easy pairs.

People find absolute value hard to judge, so they compare options that are easy to compare とあるので D。

Q3. What do the 2014 and 2025 studies suggest?

1. AThe decoy effect is often weaker than the famous example suggests.
2. BThe decoy effect works in every situation.
3. CWine buyers never compare prices.
4. DAriely's demonstration was a large scientific study.

91回中11回しか効果が出ず、実際の販売では約1%だったことから、有名な例ほど強くないとわかるので A。

Q1. Why is the decoy effect theoretically important?

1. AIt proves people always act rationally.
2. BIt violates the principle that adding an option should not increase an existing option's share.
3. CIt shows that prices do not matter.
4. DIt explains why magazines are expensive.

it violates a principle of rational choice: adding an option should not increase the share of an existing one とあるので B。

Q2. What weakness of the Economist example does the author point out?

1. AIt was a classroom demonstration in a book, not a peer-reviewed study.
2. BIt used too many students.
3. CThe prices were not realistic.
4. DIt was carried out in a supermarket.

the Economist example was a classroom demonstration reported in a book, not a peer-reviewed study とあるので A。

Q3. When did the decoy effect largely disappear in Yang and Lynn's research?

1. AWhen prices were very high
2. BWhen there were only two options
3. CWhen students made the choice
4. DWhen products were shown with pictures or verbal descriptions

the effect largely disappeared when products were presented with pictures or verbal descriptions rather than numbers とあるので D。